Running totals of a single field over multiple messages
I have an invoice system set up for a special event where multiple suppliers are selling items on a single ticket. So I can create a record with 3 separate line-item portals. Each one creates a separate supplier total. I am having trouble now with finding a way to get a running total of sales for each supplier. Essentially, I want a summary total of a single field over multiple records, but this is not working. I'm lost.