Tips are imputed and taxed from sales in the US too.

That sucks. I did work at one place where the percentages weren't set and it made for some friction because not every server tipped out BOH/ support at the same rate. The best places I worked set minimum percentages (ie, 5% to kitchen, 3% to dishwashers, etc which ended up being 15% of your sales) and got could go above if you wanted such as if the kitchen saved your ass. It made for better morale. I worked at a couple places where it was a free for all and BOH/FOH were always fighting and turnover was high