No.

Seriously, people?

If you want to buy some books, you buy them all at once. That is, you set them on the counter, I ring them up, you pay me, I bag them, and you leave. You don't bring up some books, have me ring them up, tell me to bag them, and then let your four year old granddaughter prance around the store with them for THIRTY MINUTES while I wait for you to decide what else you want. That is not how it works.

Also, if you have store credit, you either give me your credit slip or, if we have it on file, you tell me so and give me your name so I can like, I don't know, look it up? I mean, that sounds pretty logical to me. But you know what isn't logical? Staring at me blankly for about thirty seconds, then sputtering, "what do you mean it's thirty dollars? We're part of your book club thing!"

"'Book club thing'? You mean you have credit?"
"Yeah, that."
"Do you have your paper, or -"
"You never gave us one!"
"Okay, then you left it here?"
"Yeah!"
"Fine. What was your last name, please?"
"I don't know."
"You don't know."
"I think it's under [name]."
After a few moments of searching:
"Okay, found it."
"Why didn't you have it before?"

Yeah, um, that's annoying.

"Because I'm not actually telepathic. If you have credit I need you to tell me."
"...Oh. Well, we didn't know that."
"No problem."

I applied their credit, adjusting their total accordingly, and naturally, Grandma Genius (who, by the way, was neither senile nor particularly old, just dumb as a freaking post) decided to pay me almost exclusively in change. I swept the change into my hand one veritable pound at a time, and she shoved four pennies across the table with a condescending:

"You forgot these."

I raised my eyebrow. "Actually, I didn't. But thank you for assuming otherwise."

Luckily, she didn't get it.

And yes, I know that one day my attitude is going to bite me in the ass, but I don't care.