Commission Calculation at 2 different rates

Hi,
I am sure this wont be unique scenario and someone might be able to help.
I am developing a template that calculates the commission for sales guys. Situation is little tricky!
Full Commission Rate = Target/Commission
Half commission Rate - FCR/2
Until rep hits 50% target, he gets paid at Half Commission Rate (HCR) and more than or equal to 50% than FCR
To top it up, moment rep hits 50% of his/her target, clear any previous payments made at HCR calculation!
Trying to develop a simplified version and my logic is gone on holidays, and would appreciate someone's input. Test file attached.test.xlsx
Thanks in advance
Ta

test.xlsx
Please see the attached file.