I've traveled to more than a dozen countries over the past two years and I've NEVER seen an ATM that asks me what currency I want to be charged in...
One look and I saw the massive rip-off for what it was(conversion from Czech Crowns into Swiss Francs) and avoid Citi ATMs like the plague since then.
As I recall the difference on withdrawing the equivalent of 500EUR would have been an additional ~50EUR for the convenience.
Thanks, but my local bank does such conversions just fine.