Similar to deductions for uniforms and cash-register shortages, the employer may be allowed to make this deduction. The only requirement under federal law is that if the employer chooses to have you bear the cost of the tools needed for your job, the deduction cannot take your pay below the minimum wage and/or reduce your overtime compensation. However, if you make more than the minimum wage, so that the deduction does not take your pay below the minimum wage, the employer is legally entitled to deduct the cost of the cash register shortage from your pay.
Some states have laws which more narrowly limit the deductions which may be taken for required tools and other work-related items. If you still have questions about your state's laws relating to deductions, then you may wish to contact the agency in your state which handles wage and hour/labor standards violations, listed on our site's state government agencies page.