To be able to track contacts from different countries and process payments for them in their local currency, use a feature of Sumac called Segments.
In Sumac, you can group contacts together under different segments, and you can define as many segments as you need ("EUR", "GBP," "USD", etc). Once you've defined all your segments, you can assign a segment to each contact in the Sumac database. Each segment can also have its own unique payment processor. You can either use separate payment processors to handle financial transactions in each currency, or, open up a few accounts with the same payment processor, using each account to process transactions in different currencies (please contact our supported payment processors for specifics). Link the appropriate payment processor(s) to each of your segments, and then you’ll be able to process payments in each contact’s corresponding currency.
Keep in mind, Sumac stores currency as a numeric value (i.e. it does not store amounts in any specific currency, just as a numeric value). However, if you have a contact record in the "EUR" segment, for example, it is understood that numeric values in fields designated to represent monetary amounts would be in Euros.