Report to Show Revenues and Costs Directly Attributable to a Customer

The Customer Profitability Report answers this with just some few things to do:
 
1. On your Bills, go to the Expenses & Items tab. Notice that there is a Customer column. Make sure you enter the customer name in this column so that the cost would be linked to the customer.
2. Now run the Customer Profitability Report in Reports > Customer/Receivables .
3. Click View Detail. Notice that under the Total Cost column you can see the Bills and under the Total Revenue column you will see the Cash Sales and Invoices. This report will now be more useful in assessing your customers' profitability in terms of directly linked costs.