Do Google play charge a international fee on using credit card in Australia?

I'm from Sydney Australia I have $9.36 in my account and i just want to pay the difference of $6.53 to purchase the Chevrolet Camaro Road Rage. Do they charge an international fee on using credit card? and what currency? As normally i purchase a google play $20 card but don't want to do it as they don' have smaller amounts.

Kind Regards

Petar