What you want is probably in the AR_InvoiceHistory... tables, but how to properly link the tables together is not necessarily intuitive, plus the data set could be huge / crash Excel.  I'd suggest contacting your Sage partner for some hands-on assistance.  The data you need is stored in multiple tables and best handled by an expert, familiar with your specific data.  

The question is do you want the sales as posted to a specific GL account or sales as in invoices per customer.

Great question.....I am required to download 3 years of sales transactions to a customer/invoice/product/amount level and build it back up for audit purposes.  We will also want to pull sales tax if possible.   A lot of detail.  My goal is to extract as much as possible and use what I need. Thank you!

I would use either MS Access or SQL and extract the AR Invoice History Header and AR Invoice History Detail and the AR InvoiceHistoryTax Summary.  Use a query to build a single data set.  

(Be careful... if Multi-Currency is installed, the invoice history data will be a mix of currencies, and you'll need to pay close attention to conversion issues, when reconciling to the GL.  This kind of system specific possibility is why I suggested talking with your Sage partner).