Need a formula to figure out a pay rate for a tiered bonus program

Okay well im not only new to this forum but new to forums in general, Im considering changing my employees pay scales and I generated a excel page that figures out their pay along with a few other mock ideas. My second mock pay would consist of a tiered bonus program and based off their total sales they would fall into a certain bonus percentage. Attached is everything set up and I highlighted in blue what I can not solve.

Thanks,
luke