Is it really 5% of their 30% profit and not 5% of the overall price?

I'm really curious because I don't know all the details of LinkShare but the way I understood it, it's the same program for apps and music and everything else in the iTMS. Thus, I'd be surprised that the 5% is of Apple's profit since either:

-that would make apps different from music,

-or it would let us know the profit made by Apple on music as well, which I always thought was unknown.