Blades and spades
The dragonborn don’t use coinage or even precious metals for their currency, instead using thin pieces of brass in the shape of knives known as blades as well as a smaller denomination known as a spade due to its shape. Both are backed by different things: A blade is worth one pound of wrought iron ingots while a spade is worth one pound of grain. Both currencies can be traded in for the equivalent amount of the materials they represent within dragonborn lands. Though it differs based on the supplies of grain at the time, ten spades is generally worth a single blade.
Blades and spades are not convertible into other currencies usually, but since you can convert them into grain and iron, you are able to trade those with other people for the currencies of their lands. Because of this, two blades are roughly equivalent to a sixtieth stater.