Cumulative tiered commission with no quota

Hi there, i need some help calculating tiered cumulative commission structures. I saw alot of help online but many workbooks contain quotas.
and i am unsure how to proceed.

Basically i need to calculate the monthly comms where there are 3 tiers.

$3001 - $10,000 = 60% comms
$10,001 - $15,000 = 70% comms
$15,001 and above = 80% comms.

so if someone made $20,000 , the payout shd technically be something like this

[(10k - 3k) * 60% ] + [ (15k - 10k) * 70% ] + [ (20k-15k) * 80% ] = $11,700

is there a simple table that i can input daily sales to calculate this? and also to edit the % commission if i wanted to.

i did try other formulas that i saw online but they dont give me the flexibility of changing the commission payout

for example if i wanted to change it to this

$3001 - $10,000 = 10% comms
$10,001 - $15,000 = 10% comms
$15,001 and above = 15% comms.

pls help !

See if this gets you anywhere close. It checks out against your 1 example.

It's a quick adaptation of something I did to lookup in tax tables!