> I would like the table to hold the invoice total but I can't figure out how
> (the actual equation) or where to put it so that it auto sums the individual
> items and puts the totals in.
That's an easy one.
You DON'T!
Access is not a spreadsheet and has it's own rules of usage.
Do not store calculated data.
Whenever you need the results of a calculation, calculate it.
Store the various data that make up the total, i.e. [Price],
[Shipping], and [SalesTaxRate]
Then, in a form or report, calculate it in an unbound control.
Set the control's Control Source to:
=(Nz([ItemPrice]) + Nz([Shipping])) * [SalesTaxRate]
In a query it would be:
Total:(Nz([ItemPrice]) + Nz([Shipping])) * [SalesTaxRate]
Note: Look up the Nz() function in VBA help.

Signature
Fred
Please respond only to this newsgroup.
I do not reply to personal e-mail