So um...
typically when people talk about currency changing its value in a game there are three types of tasks:
Gold inflator(reduce value)-Adds to the quantity of gold... mission tables, pants shuffle, and looting are good examples
Neutral transactions(don't effect value)-Transfers the gold from one location to another without loss... opening a trade with someone in which you pass gold. Putting it in your bank and taking it out
Gold sync(increase value)- Gold being used in a transaction in which value is lost(Buying items off venders, Buying consumables(including mounts), Using the AH
Some syncs are unnoticeable(mailing costs for example). Some are HUGE(5million mount)
I honestly have no clue if Bliz takes a cut on tokens. But either way it is either Neutral or a Gold sync.