No, it is not legal to withhold an employee's paycheck, even if the employer believes the employee owes it money. The correct response if your employer believes you somehow cost it money is to sue you for the amount--though it is unlikely, at least based on what you write, that you would in fact owe the store anything.Since the employer may not withhold your paycheck, you could sue the store (including in small claims court) to recover your pay.