Is it legal for an employer to force employees to pay for unsold product?

My sister's employer is telling his employees that the cupcakes they are making are unsatisfactory (despite their faithful adherence to the company's recipes). This is often based only on a single customer's complaint that a cupcake did not "taste right." He has also stated that the product was unsatisfactory because he felt the batter was too dark or light in color. The production team is required to taste-test each product before placing it in the sales area. The employer is threatening to make the production team (including my sister) pay for the loss of all these cupcakes (averaging $210 per batch). He says they will need to pay him for any product he feels is unsatisfactory, which seems to be based on his personal whim and not necessarily even a customer's opinion. This means the cupcakes may not even be allowed to reach the sales area. There is no written employment contract involved between the employees and the employer (who is also the owner). I believe he would be allowed to terminate any of his employees at any time for almost any reason, but I can't see how it would be legal for him to make the employees pay him for a correctly made product that he seems unable to sell. Is this legal in the commonwealth of Virginia? Thank you for your time and effort.