How to get always the main currency in the backend

Hi, before buying your PRO plugin I have some Pre-Sale-Questions:

The main currency of our shop is Euro. But our users can buy from everywhere. So as secondary currency we want to allow US Dollar. I see with the Free version that in the checkout the user can switch the currency. In this case he can pay from everywhere in US Dollar.

But in the backend and on the invoice, I always need the currency in Euro. It is possible to allow users to pay in Dollar, but showing the calculated Euro currency data in the backend?

I cannot figure out it with the free version.

Thanks in advance!