Sumx total in each row

Hello all,

In the following image  you see for the customer 301000133 for each invoice number the outstandin amount.

The outstanding amount is calculated by invoiceamount - paid.

The current issue is that i can not return the total value of 1.969.60 for each row (see image 1). 

How can i get the result of 1,969.50 for each row (see image below)? 

Thanks in advanced