I do not practice law in Virginia but that is a good question that can arise most anywhere. I think most anyone paid on commission is entitled to receive documentation showing how commissions were calculated. How else do you now if you are being paid correctly?
Most anyone working on commission should be clear from the start (and preferably have in writing) the terms of their pay plan including an explanation as to how costs, profits and commissions will be calculated and what books or records will be kept to prove math was done correctly.
If employer refuses to give you that information it may be a red flag. If the employer expects you to blindly trust its calculations, and you have no means to independently verify anything, the employer may well have an enhanced or even a fiduciary duty to provide an accounting.