I think this thread is effectively the same thing you're looking for.
you want a subtotal for each section that includes Equip Price, labor Price, and Taxes for the items in the section.
the easiest way to do this is to add a calculated field with the "TotalitemPrice", bind to that, and set summary properties to subtotal like the equipment and labor properties.
This thread discusses how to get the calculated field:
Proposal with "Options"
-R