Random credit card thought

OKay, I was buying some software today (to go with my new computer - I'll post on it when I have it set up and all my old programs/files transferred), and I noticed something. Usually, when you pay with a credit card, the screen has something along the lines of "Is this amount OK?" Presumably, this helps prevent fraud, though I doubt that many people actually pay close attention.

Anyway, this screen said something like "Is this the amount that you would like to charge to your card?" and my first thought was "No, I'd like to charge nothing, and get this item for free."