Add Totals to a Report
Ensure you are in the New Report or Change Report window.
In the field listing, click in the Total column of the row you want to add totals to.
Click the drop down button to display all the options.
In the Options window, click in the Sum check boxes for the Report and for the Group.
This will total the column and for the entire report.
Click on OK to close the Options window.
Notice that the field table is updated with the totals icon to indicate that some sort of totals are defined for that field.