They should have proof that you are paid in Check/ Cash as per your service. If they don't have this proof it's irrelevant for them to ask this question.

 thanks raju for the reply, but the fact that i was inside the store and was busted and have a record on background check is worryin me...

fizi water,
                   is your case dismissed or not?have you ever arrested?(this question will surely come?),answer them yes if you were.make sure take the original copy as well photo copy of the dismissed paper,its good if you take attorney with you.they don't ask you how did u know about the register and bla bla.if they also just answer them easily you were there to visit him n make some kind of story.good luck