I'm trying to work out a calculation where I'm trying to use the IF function to auto calculate a result.

Here is my formula:
=IF((D10*40%)+SUM(F$2:F9)<=18000,+D10*40%,IF((D10* 40%)+SUM(F$2:F9)=18000,+J$2-SUM(F$2:F9),100))

What I'm trying to accomplish is calculate a percentage dollar amount (40%) and then add those amounts until the SUM of the column hits $18000. This means that the amount calculated that hits $18000 will be less than 18000. After the SUM hits $18000 rather then calculate the percentage it should enter $100 into the cell.

I know this should be something I can do it just has me stumped.

Tim