Title: Money in Italy: Banks, ATMs, cards & currency exchange
Article Snip: "...Always choose to be charged in EUR, the local currency
One thing you should be aware of if you use a credit or debit card abroad, is something called Dynamic Currency Conversion (DCC). How it works is that when you pay, you might be asked if you want to be charged in your home currency. While that sounds nice and easier to understand, it means that the exchange rate applied is chosen by the retailer's bank. As a general rule, this won't be as good as the rate your own bank would give you (after all, it's in your bank’s interest to keep you happy).
Instead, always opt to pay in the local currency to make sure you get the best deal. ..."