What your friend has to do is up to her and to her boss. She should talk to her boss so he can answer the question.
What the customer did is wrong and should never be tolerated, but neither should the "smaller" offences. What to do in which case is something she has to ask her employer.
She might be not the only one in the store that has to deal with it. Talking with her employer might result in a general approach for the employees in case of a sexist or racist comment/action from a customer.
