I have a bit of a quandry with this one. I have a spreadsheet I need to
calculate commissions with. First the salespeople enter in how many sales
they get each day which then totals at the bottom. The way it works for most
of these sales is if they get between 1-4 sales, they will get $2 for each
sale. Above and beyond 4, they get $5 for each sale. I have the forumla
setup like this:

=IF(B28<4,B28*2,6+(B28-3)*5) where B28 is the total number of units sold.

The problem is I have one product where the commissions are on three tiers:

1-5 units= $7
6-10 units= $10
11+ units= $13

How would I calculate this?