Can you create a coupon code for collecting taxes only during checkout?

Question

Is it possible, using native Magento functionality only, to use a coupon code that will reduce the grand total to a specific amount, and only charge them for taxes?

The use case is:

• Customer buys something on a 3rd party site for a reduced price.
• Let's say they pay $100 for a $200 product to use round numbers
• They don't pay taxes there
• They get a coupon code which they can use to redeem the purchase on our site
• When they checkout on our site, they may have to pay taxes

It's easy to create a coupon code for the $200 value, but the problem then is that the grand total on the order becomes $0 instead of $100.