Eliminate taxes if when using the order fixed amount off promotion the subtotal remains at zero

Describe your bug or feature request.

If you use the promotion OrderFixedAmountOff with an amount equal or higher than the subtotal amount the taxes remains and are not recalculated

If a bug, provide steps to reproduce it from a clean install.

Add to the cart a product, use the OrderFixedAmountOff promotion with a value equal or higher than the amount of the product/cart. You still will have the taxes being applied despite the amount of the subtotal being zero.