Sory if I missed it, but I don't think anyone mentioned a common practice at merchants in Europe (and some ATMs): You will be offered the "convenience" of paying in your own country's currency. What won't be obvious (and sometimes not even shown) is that the merchant and/or their bank gets an extra bonus by asking your bank for more dollars than they should. Sometimes, they won't even offer; they just do it and hope you don't make them take it back. One McDonald's manager even told me the lie that they were required to do it.

Sorry if I missed it, but I don't think anyone mentioned a common practice at merchants in Europe (and some ATMs): You will be offered the "convenience" of paying in your own country's currency. What won't be obvious (and sometimes not even shown) is that the merchant and/or their bank gets an extra bonus by asking your bank for more dollars than they should. Sometimes, they won't even offer; they just do it and hope you don't make them take it back. One McDonald's manager even told me the lie that they were required to do it.