So say you're going to pump $100 worth of fuel, and stop when the tank is full? You'll only be charged for what you pump.
Didn't work that way for me - last time I was filling up, I did pay a bit more before than fit into the tank and checked the bank account later - got charged for the full amount.
That's weird, they should just put a hold on for the amount you entered and then charge the actual amount pumped. Sometimes the holds appear as charges? Did you get a refund later?
Ah, that makes sense. Is this the case everywhere in the US?