I haven't tried it yet but under FAQ's there is the charge for currency conversion.
"What currencies can I make shop purchases in?
You can make purchases in any currency supported by your MasterCard-enabled merchant. Purchases in your card's currency, USD or EUR, are free. Purchases in any other currency other than the currency of your card incur a currency exchange fee of 2.95%."
RE: The Old Dog Advises: Get a Debit Card And Spend Some Steem. It Will Empower You!