Two weeks ago, my brother-in-law stumped me with a Capital One credit card in euros or dollars.
Imagine my embarrassment when I couldn't help him answer that question.
To keep things interesting, he alternated between euros and dollars and I promised to find out the difference when I got back stateside.
First stop was Capital One. According to the company, international retailers can offer cardholders the choice to pay in their home currency or the currency of the retailer. If you choose to convert to your home currency, the retailer (or the retailer's bank) can charge you a conversion fee.
Note: That's not same as a foreign transaction fee, which is charged by some card issuers for every purchase you make outside the U.S.
"However, as a Capital One customer you will not pay this fee since Capital One does not charge any foreign transaction fees," noted Sukhi Sahni, a spokeswoman for Capital One.
So my brother-in-law should have charged every purchase in euros and avoided the retailer's conversion fee.
If you carry a card that does charge a foreign transaction fee, it may be cheaper to have the retailer convert the currency at the point of sale. It depends on the conversion fee. Fortunately, Visa requires retailers to provide the consumer with the exchange rate plus any commissions or fees being charged, says Ted Carr, a Visa spokesman. That way, you can compare the retailer conversion fee to your foreign transaction fee.
American Express cardholders don't have to worry about making a choice. The issuer prohibits the practice, according to company spokeswoman Diana Postemsky.
Discover and MasterCard didn't respond to my inquiry about their policies in time for publication.
Have you run into an odd credit card dilemma overseas?
Follow me on Twitter: @JannaHerron