So I received a few "song credits" with a promotional iCoke promotion. Though it was advertised as one free iTunes song, can I use it for an iTunes app instead? The equivalent of a .99 app. I've come to understand that you cannot "combine" apps inthe sense to reduce a price (like using five iTunes credits for five dollars off a $10 music album. However could you (if credits for apps is possible) use five credit for a $4.99 app?