wherever we are in the world we pretty much always want our CCs charged with the local currency, then allow the CC bank to make the conversion to USD...it will most likely never be in your favor to choose to have the conversion done at point of sale (unless the vendor clearly states they will be using a conversion rate better than official rate)

but what i find different in SXM, on the Dutch side, is that some places give you the purchase amount in NAF, then do the conversion with a calculator, then charge your card in USD...i don't think i've ever had my CC charged in NAF, and have never even been asked what currency i wanted to be charged in...but i guess it doesn't matter since it always seems to be 1.79:1