If I'm not mistaken after analyzing the fees we pay credit card companies here at work...Walgreens actually LOST money by selling that product to a credit card purchase.
Reading is fundamental...
Look at how much my wife charged on the check card!
And sometimes with a check card, the store just pre-authorizes a small amount to "hold" the charge in line, until the total amount can be deducted. That happens when you buy gas with a debit card too.