Originally Posted by wantan

thanks for the info. I didn't proceed since this was the only hotel that I've come across in Hilton that does flex rates this way.

I'm using a non-Singaporean AMEX charge card, in my experience whenever there is a foreign currency transaction it converts at the current exchange rate. There was once where I requested a chargeback (foreign restaurant charged my card twice) and the amount I received was about 5% lower than what was taken due to the exchange rate and bank "admin fees".