Can taxes be totalled on separate sheet when using Excel invoices
 

Each month I create approx 75 invoices. At the end of the month I'd like to
know what my grand "sub total" is, my 7% tax total and my 8% tax totals, on
a summary sheet.

One step further, I'd like to have each month's summary sheet roll onto
another sheet or workbook even, whatever is better, as a 12 month
accumulative summary sheet.