The Zelda series tends to change from one game to the next. The gameplay mechanics might be different, the controls may be reworked, and the roles of the characters could change from princess to pirate to poltergeist. However, there is one aspect of the Zelda universe which is always the same. In every single canonical game and in most of the spin-offs, the currency is always rupees. But what are rupees exactly? And what would they be worth in the…