Hi Noele,
Have you looked at the sample forms that come built into LiveCycle Designer? Go to File-New, choose Template and there is an Order form sample that has a Grand Total field for row and column calculation. You can examine the scripts to see how it was done. There are many other templates with other features, so this is a good resource.
Hope this helps,
Dimitri
www.pdfscripting.com
www.windjack.com