Sadly, they do not. It is the base fare that counts towards mosaic status multiplied by 3.

For example, if you spend 500 on a flight, breakdown is $400 for the fare, $50 in taxes, and $50 for an even more space seat, you will receive the qualifying spend on only the $400, netting 1200 points towards qualification.

Edit: at least from experience, and I've held mosaic for 3ish years now.

Edit 2: I can not read.