Change Currency for the donations?

Hi. I'm pretty new to this Donate via PayPal thing. I just installed the module and find it very helpful. But there's one issue:

I'm German, my page is German and my users are German. So donating a beer or coffe for $1 is not very productive since both of us (my users and me) have to pay some money for the currency change from Euros to Dollars and back again. Is there a way to change from $ into €? If yes - how do I do it?

Thx. for the help.