It's bad enough we have to do some kind of cacluation when trying to figure out what costs what. I looked on my cc and they tax this shit as well!
For your shady euro like currency. For taxing the MS points as a "purchase."

For seeing HD movies.

Tax? Are they taxing using MS points to pay the tax or are they providing dollar amounts that you can calculate the tax off of?

They do this with Dell spiff points, but items are also assigned dollar values so you know exactly how much tax would be deducted from your last paycheck of the year.

This is technically a form of "income" or "purchase" and is therefore taxable -- even if you didn't spend US currency for it.