IF Command to apply a formula each time a Name appears....

Hi,

I am building a spreadsheet to help track commissions for our sales people when they make a sale. Each commission is 20% of the total sale value, and is made up of four parts, always. Each part of the sale is worth 5% (ie, 5%+5%+5%+5%). SOmetimes, one sales person will get all 4 parts of the sale, sometimes 4 people may be involved. So, I have figured out how to use an IF and Countif command, however, the command is only picking up the one instance is finds a Sales person (ie., =IF(COUNTIF(J20:M32,"Haigles"),F20*0.05). So, if "Haigles" in was involved in 3 parts of the sale, my formula above is only picking up 5%, not the 15% required. I've attached the spreasheet. Hopefully someone can help???
Thanks for your time with this.
Commissions Spreadsheet Test.xlsCommissions Spreadsheet Test.xls