I need to get a sum from multiple 'IF' cells

I have a spreadsheet with the following formula:

=IF(ISNUMBER(E5), "20.00","")

If data is entered in cell E5, the cell below it will have 20.00. If not, the cell will be blank. This is the case for columns E, F, G, and H

At the end of the row, I am attempting to get the sum of all the cells in this row.

I did the standard sum formula, but it always comes up with 0 whether or not the cells have a value present. How can I produce a sum, if the IF formula is present?


Thanks!