If no clear cut answer to what is considered "Lost Property" there is a clear case of ambiguity in what at least the drafter of this considers a contract. (Whether this is is another question.)
What I'm left wondering is what happens if you see a cash cheque for a million dollars in the waste basket... Recycle or Lost Property?
As a general rule of thumb ambiguity in a contract terms are held against the drafter of the contract. Especially when the drafter is in a superior bargaining positions (As it clearly seems is the case here.)
For your convenience I would tell you to ask your employer to give a clear definition of what you should consider "Lost Property" So as to better understand what is required of you.
Whether your employer can deduct your salary for damages they decided was your fault is an altogether different question.
Here is some quotes.
All employees are, to some degree, agents of their employers.
Similarly independent contractors will also be agents of whomever they
have contracted with. The extent of their authority will depend on the
circumstances.
ix. AGENT'S AUTHORITY
An agent's authority to act on behalf of his or her principal could be
actual, or apparent.
a) Actual Authority
Actual authority is authority an agent has because the principal has
given it to the agent. To have actual authority, both the agent and
the principal must consent to the relationship. No consideration or
payments to the agent are necessary. If the agency relationship
involves buying or selling land, the agreement usually must be in
writing. In most other cases, no written agreement is necessary to
establish the relationship.
b) Implied Authority
Implied authority of an agent is the result of authority implied by
reason of the agent's relationship with the principal of the
principal's business, by reason of custom and usage, and by
acquiescence. For example, an agent with actual authority to purchase
goods on the principal's behalf will have the implied authority to pay
for the goods either out of any of the principal's funds she has in
her control, or on credit. There is also the implied authority to
accept the delivery of any goods that she has the authority to
purchase. Similarly, an agent who has the authority to sell her
principal's property has the implied authority to give general
warranties regarding the property. If the agent possesses the
property, then she has the implied authority to collect payment.
c) Inherent Authority
In some situations, the courts find an inherent authority for the
agent to act in order to protect innocent third persons. Under this
concept, a principal is liable for the wrongdoing committed by his or
her employees if the acts were within the scope of the employee's
duties. For example, if a salesman is instructed by his employer not
to warrant the fitness of any of the vacuums being offered for sale
and the salesperson warrants a vacuum, the employer will be held to
the warranty. In this context, scope of employment means that the
employee is engaged in the furtherance of his or her employer's
business.
d) Apparent Authority
A person is normally not responsible for another's acts unless that
person is authorized to act on his or her behalf. An exception is the
doctrine of "apparent authority" sometimes used by the courts to
prevent injustice to third persons. The mere statement by a person
that he or she is an agent of a certain person is insufficient to
establish the agency. The third person has a duty to ascertain whether
or not an agent has the authority to act in a particular situation. If
the principal has led others to believe that the agency relationship
exists, he will be bound by the acts that an agent in that situation
would customarily have the authority to do.
The agency relationship would be used by the courts when the principal
has a duty to deny the relationship but fails to do so. For example,
if May in Cathy's presence tells others that she is Cathy's agent,
Cathy has a duty to deny the relationship. If she fails to, then any
third persons present might consider that May is, in fact, an agent of
Cathy's. An agency relationship may also be found when the principal
negligently allows another person to act as his agent. For example, a
stranger comes into a store when no one is present, waits on a
customer, sells a product, and pockets the money. Because it was
reasonable for the customer to assume that the stranger was a clerk,
the owner cannot force the customer to pay for the merchandise a
second time.
e) Ratification of Unauthorized Acts
If an unauthorized person acts as a business owner's agent, the
business owner can ratify (accept) the unauthorized transaction. If
the owner does this, he or she is bound by the act of the unauthorized
agent. To ratify the act, the principal must know of the material
facts involved in the transaction and accept the entire transaction.
He cannot approve the part favourable to him and deny the unfavourable
portion. A principle can ratify only legal acts.
The ratification of an agent's unauthorized acts may be by express
approval, by acceptance of the benefits of the act, or by silence when
the principal had a duty to speak. The third person can withdraw from
the transaction if he notifies the principal before the principal
ratified the transaction.
Also lastly and probably most important for your issue.
xiii. LIABILITY FOR ACTS OF AGENTS
Under the doctrine of "respondent superior", a principal might be
liable for certain acts of his agent. To be liable there must be an
agency relationship, and the conduct must be within the scope of
employment. To be within the scope of employment, an employment
situation must exist. If the agent is an independent contractor, whose
duties the principal has no right to control, no employment situation
exists and the principal is not usually liable for the acts of the
agent.
To determine if an employment situation exists, the courts not only
look at the degree of control that the principal has over his agent,
but also whether or not his agent is engaged in a distinct business,
the degree of skill involved in the duties, and the period of
employment. If the court determines that the agent is in fact an
employee and not an independent contractor, the employer (principal)
will be liable for the torts (misconduct and negligent acts) he or she
committed that injured others or damaged property belonging to others.
SOURCE
Also what I would also like to tell you is that your employer does not have carte blanche to deduct your salary for every trumped up charge they can think of.
If you have a work contract in place (I hope you do.) Then your employer is obligated to pay you in the manner that your work contract demands. So if your employer pays you less then what you have both agreed upon then you have the same remedies to your disposal that any breach of contract law provides.