IF/Nested IFs

Hi,
I'm wondering if you can help with a IF/Nested IF statement I'm struggling with at the moment.

I need to calculate how much commission is to be paid to the consultant, based on the % margin made.

IF the % margin made is greater than 15% - the consultant receives 2.5% of the total cost
IF the % margin made is between 10% & 15% - the consultant receives 2.25% of the total cost
IF the % margin made is less than 10% - the consultant receives 0% of the total cost

so far I have 2 separate columns of:
for the 2.5%: =IF(H7>15%,E7*0.025,0)
for the 2.25%: =IF(OR(H8>=10%,H8<=15%),E8*0.0225,0)
can these be merged together to also contain the <10%

Many Thanks
Chantelle