In GP10, you can print multiple sales invoices in one step. Select the Sales tile in the Navigation Pane, then select Receivables Transactions. Filter the resulting list for the type(s) of documents you want to print, date range, etc. When you have the list filtered, place checkmarks next to the documents you want to print and click Print Documents. All documents will be printed to the destination you select in the Print Destination window.
* click image to enlarge