On the folio, you say it lists all of the taxes as well as a room rate. On your confirmation email, if you scroll down, you should see "x nights at [room rate without taxes]" - does that rate match the rate on the folio? If there is a discrepancy there, you have an issue - if not, taxes change. In some jurisdictions, there are additional taxes that aren't listed in the total but are still mentioned a booking - the 20 AED fee in the UAE comes to mind.