I could have become an SC....

[XCashier]

So I politely tell him I don't want to sign up. He again tries to overcome objections and again, I say no. So he goes on again. After telling him my reason AGAIN for not wanting to sign up, he goes "That's OK, we also like people who overpay."

There's no reason for him to get snotty with you. I hate it when employees do that; that's a good way to lose a sale.

Suggestive selling is a pain in the tuchus, I agree. Just say it once, and if the customer says no, drop it. Hardselling only ticks people off, and sarcasm will likely make them put down their goods and walk out the door, never to return. I wish corporate bean-counters would understand that.