Yes, the employer can ask you to do this. If  you are unwilling to do so, the employer could fire you if he wanted, assuming you don't have an employment contract protecting your job (without an employment contract, you are an employee at will, and may be terminated at any time, for any reason--hence you could theoretically be fired after you paid to rekey, if the employer wanted to do that). The employer could also take a lesser action against you, like demote you, reduce hours or pay, etc.  In addition, the employer could sue you for the cost of rekeying the store if you don't pay voluntarily--you apparently negligently (carelessly) caused him to have to expend money to rekey (to avoid a security issue), which would very possibly provide grounds for a successful lawsuit. What he can't do is unilaterally deduct the cost from your paycheck--that is against the labor laws, unless you agree to a deduction.