Auto sum rows with variable content and amount of rows above

Every day at work I run a report that requires sum calculation every few rows. However, the number of rows above each sum have varying content and number of rows, so subtotalling wont work. I have been going through and pressing autosum in every sum row cell and dragging it across it is very time consuming and frustrating. Then I have to copy & paste the sell through formula in the last 2 columns.

Can anyone help me with how to get excel to recognize the rows that need summed and that it should only sum the rows after a previous autosum? I'm really not sure what the best method is to get these sums and sell through percentages.

I hope I have explained myself ok...

Thank you

Attached is an example file:

Mock Style Report 2.xls