Going forward--that is, after the employer announces such a policy--it may be possible for him to do this; employers have enormous discretion in setting work rules and policies, including making people make up for charges and shorts. (In terms of *how* to properly do it, the employer technically may need to structure it slightly differently than simply taking the money directly out of your paycheck, but that doesn't change the fact that a employer can require employees to make up for costs, including cash shorts, that they cause.)You've identified practical problems--the encouragment of stealing; how to prove who is responsible; etc. And if you refused to allow the boss to simply take the money out, you might get involved in litigation with her, with--if she pushed the matter--you each trying to prove your case.But again, those issues, while significant, are practicalities. An employer can make employees responsible, as long as the policy is clearly articulated, for shorts and costs.