Just as a follow-up and as we all suspected, the NTD 5500 rate was honored, and the transaction finally posted to my account at $183.07. The Visa calculator doesn't have TWD as an option to see the exchange rate, but I think Visa used 30.04 TWD = 1 USD for September 15th based on two other transactions that posted today from Watsons (my personal store ) and Taiwan HSR.

Had this transaction been hit with DCC the hotel would have made an easy $8.96 off of me at a markup of 4.89% compared to the rate Visa used.