My friend told me that when you buy something in a foreign place with your card, and the machine offers you to pay on the local currency or on your currency, you should choose the LOCAL one. Basically when you do that, your card is the one doing the exchange, while if you choose your currency, they do the exchange and you pay that on your currency. Their exchange is likely to be worse than your card's exchange.
So, I just tested this. I purchased a flight ticket on Cathay's website and the default was HKD. The total was 2638 HKD. They give you the option to pay with USD, but when I selected that it said 348 USD. Google exchange rate was giving actually 338 USD. So, I did what my friend suggested and picked HKD. Later checking my credit card bill, sure enough, I had actually paid 338 USD! :)
Great!
