Legal Question in Employment Law in California

Not likely. Especially if you were following your company's procedure for accepting credit card payments. It is possible their taking of your wages can result in a wage claim against the company. The California Department of Labor, Labor Commissioner's office handles such claims, and individuals can represent themselves at those hearings. But...be careful. Taking such action could result in retaliation by the employer, such as change of duties, schedule, or even termination. Even though such action would be illegal if retaliation, it is not always easy to prove there weren't other valid or justifiable reasons for such action, and you could wind up out of work.

Employees are responsible for loss or damage only if they are guilty of 'gross negligence' or misconduct. This doesn't fall into those categories. That doesn't mean they can't fire you. You're an 'at will' employee that can be disciplined or fired any time for any reason, other than illegal discrimination under the Discrimination, Civil Rights, or Whistle-blower, or similar statutes.