I usually pay with my CC for the reason stated above. I could pay with cash I guess, but I
A) dont want change which I will most likley just loose.
b) Dont want to carry around large amounts of cash or go to the bank every few days
c) like getting 1% back.
d) hate the people who pay with a check and decide to start writing the check AFTER everything is scanned and take their sweet time about it too. Or pay with cash, but have to make exact change and start counting pennies about the same time the person writing the damn check does.
It is faster, 1% cheaper, and more efficient and I have never carried a balance even one month, so it doesnt cost me any more. So that is why I use my CC to buy groceries, and other stuff for that matter.
I do wonder how many people are actually paying off the balance at the end of the month though.