"Please note: GREED works with bills of many different currencies (Danny used to do it with Monopoly Money when he was a kid).
The key is that the bills you choose to use all have to be the same dimensions.
The color of the bills is less important. You CAN ABSOLUTELY use several different colored bills. The only difference is that with multiple colors in play you'll need to adjust your finger position slightly during the third phase."
I don't know what euros look like. I assume they will work though.