Currencies for invoicing in WordPress
In the Invoices menu, select Settings, and then go to the Currencies tab.
By default, there are 3 currencies: PLN, USD, and EUR. You can add more currencies from the list and set Currency position, Thousand, and Decimal separators.
You can change the order of currencies when issuing invoices. Just drag and drop. The first position will be your default currency.
By default number of decimals is set to 2.