My American Express has an offer to spend $5 on iTunes and get $5 back. Which is sweet, almost $5 free. I currently prefer to buy gift cards and load them to my account rather than put my credit card on file, however I am adding it for this particular offer, but I don't know how I can make it so I don't use the $20 or so of iTunes credit and charge it straight to my card. Is this even possible?