What is the purpose of the conversation?

M: Will that be cash or charge?
W: I want to pay by check if I may.
M: Certainly. That’s cash, then.
W: Cash?
M: Yes, Both money and checks are considered as cash. Only credit cards are charge.
W: Oh.
M: Just make the check out to the Family Store.
W: Okay.
M: And I’ll need two pieces of identification. A driver’s license and a major credit card.
W: Well, here’s my driver’s license, I don’t have any charge cards.
M: I think so. I need two numbers. Your student number is on the ID, isn’t it?
W: Yes, it is. Do you need anything else?
M: Just put your telephone number on the front of the check.
W: Okay.
M: Good. Now let me give you your license,’ your ID, and your package. And thank you for shopping at the Family Store.
W: Thank you.