Most races have their own style of coin, but because of it's ease of use, they all tend to be a mimic of Ixxar economics. Ixxars have 4 denominations of coins, each coin having a certain mixture of gold and another metal for base, separated in multiples of Five.
The Bit: Smallest form of coin, a bit is usually the size of a thumb nail made with 10k gold. In Annalow, a bit will buy you a simple meal. Another bit will get you a pitcher of beer to go with it. Other places may go as far as three times that, depending on the strength of their coin. Annalow is a very rich city-state, being a center for trade.
The Piece: A Piece of gold is about the size of a bottle cap, made of 12k gold. It is always used to denote 5 bits. A middle class merchant in Annalow earns about 18 pieces of gold a month.
The Horn: These are about as big as a US Quarter, but thicker and made of 14k gold. Horns are used mainly by banks and merchants to transfer high loads of currency in small packages. They are worth 5 pieces or 25 bits. Horns, by the way, in the Norther Borc lands are Actually Horns from a stag.
The Crown: These heavy coins are the size of a thick US Half-Dollar and are made of 18k gold. Crowns are so called because usually only royalty sees money in such a big denomination. They are, of course, worth 5 horns, 25 pieces, or 125 bits. Some military will receive annual pay in crowns, but the coins, themselves, are a rare sight. It's like finding a one-thousand dollar bill.
After the Crown, gold is simply kept in ingot form of 24k gold. There are pure gold coins, but no one has used them for thousands of years, and when found, they tend to get melted down into ingots anyway.