Row Grand Totals are rows containing an automatically calculated sum of row field totals. Column Grand Totals are columns containing an automatically calculated sum of column field totals.
Grand Totals are displayed in the data area highlighted with the light yellow color when you add any data fields to the Row Fields, Column Fields, and Data area in the Pivot Grid view of the SQL document.
Besides automatic grand total values you can get custom totals for a required field. They are calculated based on selected summary functions.