FN5. So how is the Vietnam Dong exchange?

The answer to that question is very straight forward - don't even bother to change to USD and later change to VND in Vietnam.

Exchange rate at the My Money Master

 The reason is because, the money changer in Hanoi actually charge us 5% for the amount of Dong you supposedly bought.  This cut down the profit margin that I have calculated prior to the actual transaction.

For this matter, my wife's method of buying VND directly is much better and less cumbersome.

But the good news is, USD is accepted everywhere in Hanoi especially at the mall and airport.  Just be careful of the exchange rate when you want to pay in USD if the price tag is displayed in VND because you don't have the negotiation power at that time.