The Altera Chronicles
There is no universal “Gold Piece” standard on Altera. Nearly every independent nation has its own currency system; most have exchange banks that will trade foreign currency for local, at a price.
The typical exchange fee is anywhere from 5% to 25%, depending on the amount being exchanged and the vendor’s attitude at the time of exchange. (Diplomacy checks, people.)
(Will add more details when I get it ready for this format.)