sort of the field area's totals in pivot table
 

Hi,
I am looking for a solution how to sort of the field area's totals in pivot
table .
My last fields are code number of the customer, customer name, date of the
puchase, name of product and total amount of invoice.
And last field is about sales amount and I get the sum of them. But I
could not succed to sort them according to the their total.