You might notice that when you run the Detailed Sales Report (or a custom report based on it) that you get a different total for sales than when you run the Detailed Sales with Customer Data Report.  This is because the Detailed Sales do not include sales of items that are not contributing to sales. Examples are Deposit items for a rental and Voucher/Gift Card sales, which are technically a liability.  The Customer Data report does include these items, which causes the difference.