Grouping customer transactions, then sorting. Please help.

[dolphinprinting]

Hello,

I was just looking at a post made: "Sorting groups of rows by a cell in that group". I took a look at the example sheet posted but am not understanding how it works. I have a sample excel sheet that I was hoping someone could help me out with. The information is a Customer Sales Details report from Quickbooks that we are wanting to group the customer, all transactions made and subtotal. Then sort by the highest subtotal with keeping the group in the same format. Does that make sense?

Below is a link to a small portion of my sheet as it is 70,000 rows.
http://www.dolphinprinting.com/Files/Sample.xlsx

Thanks

Tyler