Bull Shit payment: 5% tx fee hahahahahahahahahahahahaahahahahahha Mountain View hahahahahahahahahahahaahahaaahah
5% is the cap, you do not always pay 5% of every transaction. That TX fee includes credit card fees they might have to pay to complete your transaction.
For instance, when I pay Google for API services, there is a 0% fee on google wallet.
YMMV depending on who the vendor is, and the method of payment.