it depends on your location:
for example, in california, employers may NOT take deductions from employees or charge them for accidental losses. of course, they can fire employees who make mistakes, but a negligent mistake ("oops") must be swallowed by the employer as a cost of doing business.
but, for example in florida, employers may take almost any deduction from your pay as long as you end up earning at least the minimum wage. unlike ca, fla doesn't limit the employer's ability to take unilateral deductions.
so, call your state labor agency to see what the rules are in your state.