Greetings,
I use to have this problem intell I did the following. Keep in mind you cant do this on the screen but only in the report
I have a landscape co, so some times customers want to see what it will cost for just the lawn or just the patio. Go into your estimate table and create a field called Phase or what ever you want to call it. Then add that new fieled to the grid in the estimate screen. When a customer wants to add somthing to the lawn phase i just enter a 1 and that will group all the ones togehter in the report. When the estimate prints it will group all the 1's together then the 2's togehter with a sub total for each group and will have a grand total for all the groups at the end of the estimate.
If you know how to filter the grid, just enter a 1 in the field collum , refresh it and it will total up just the 1 group. I use numbers group for example, 1 = Lawn section 2 = Patio section.
Instead of group you could also use that field and number it yourself meaning as you add a line item the first time number each one like 1, 3, 6 and space each nunber our so you could add another line item. Then when you print the estimate you can make it so it that new field will print in that order.
Good luck
John M