In my constructed world, they use three different coins. The coins would be worth (about) 0.05 USD (called a pesokt), 0.60 USD (a dolundar), and 1.20 USD (a sterllo), respectively.

Though, how they'd know it as 30 pesokt in a dolundar and 2 dolundar in a sterllo. There aren't other coins in this system, though in a related country they use the dozabi, which is worth about 0.002 USD.

I'm not sure if this is not calculated enough, maybe it seems too calculated to be natural, or if it makes any sense at all. [I'm thinking of changing the pesokt to be 20 in a dolundar]