first step we have to create a window schedule. (the project must have windows!)
Now, when you reach the schedule properties, add some fields like family and type, count an cost.
goto Grouping/Sorting tab, sort by: family and type and uncheck itemize every instance
and if you click ok, this is the result so far:
Now what we want to do is create a new field with the total cost of every type of windows we have. Go to the fields in view properties and select calculated values.
Create a name for the field, select currency in the Type option and in the formula just type the name of the Cost field. Basically we are just duplicating the Cost field.
Finally, select the formatting tab, chose the new field called Total Cost and check the Calculated Totals.
If you didn't select a currency in the project units, you can definite here just for this field by choosing Field Format and unchecking the "use project settings".
This is the final look of your sechedule with both cost per unit field and total cost per type of window:Source: badrevit.blogspot.com.