"12% of total sales ..."

Me: That doesn't sound too bad! They keep 12% of the profit, leaving him 88%!

".. and then 15% [after that]"

This reminds me of the scene in Queen of the South. FL (female lead) is new to power, negotiating some deal.

Guy: How much?

FL: Unsure how much to take 10%.

Guy: Thinking her cut is only 10%, seeing her as weak Oh.. heh.

FL: Detects her mistake For you.

Guy: Face gets red, angry But.. but..