Calculations
RadPivotGrid can apply different calculations on your data. Instead of presenting the whole Total number you can show other information  for example, what percentage of the GrandTotal is the value in particular cell.
Total Calculations are applied through the TotalFormat property collection exposed on their PivotGridAggregateField class. TotalFormat features the following properties:

TotalFunction – what type of calculation should be applied to the aggregate values

GroupName – if any, which group the calculations should be performed against. For example, the DifferenceFrom operation will calculate the difference between the current aggregate value and the aggregate value for the specified group

Axis – which axis the calculations should be carried out against. For instance, the DifferenceFrom operation requires a group to be specified but this group can be present both on the Rows and Columns axis.

Level –sets which field to apply the calculation on  for example if you have three RowGroupFields, the first one will have level 0, second one  level 1 and the third one  level 2.
Calculations
There are several predefined calculations that you can use. To explain each of them we will use the RadPivotGrid below and we will apply the calculations on it to show how they will modify the view of RadPivotGrid:
 DifferenceFrom  instead of showing Totals in the cells you can show how items differentiate from a particular group. In the example below we have set DifferenceFrom "Pen":
<telerik:PivotGridAggregateField Aggregate="Sum" DataField="Price">
<TotalFormat TotalFunction="DifferenceFrom" Axis="Rows" Level="0"
GroupName="Pen"/>
</telerik:PivotGridAggregateField>
You can also set DifferenceFromNext or DifferenceFromPrevious  this way each cell will show how the value in it differentiate from the value in next/previous cell. For example we can set DifferenceFromNext for our Rows and here is the result:
<telerik:PivotGridAggregateField Aggregate="Sum" DataField="Price">
<TotalFormat TotalFunction="DifferenceFromNext" Axis="Rows" Level="0"
GroupName="Pen"/>
</telerik:PivotGridAggregateField>
 PercentDifferenceFrom  the logic behind this calculation is the same as DifferenceFrom, but instead, the difference is calculated in percents.
<telerik:PivotGridAggregateField Aggregate="Sum" DataField="Price">
<TotalFormat TotalFunction="PercentDifferenceFrom" Axis="Rows" Level="0"
GroupName="Pen"/>
</telerik:PivotGridAggregateField>
You can also set PercentDifferenceFromNext or PercentDifferenceFromPrevious and this way the value in each cell will be the difference between its value and the value in next/previous cell, but calculated in percents.
 Index  calculates a weighted average by using the following formula: ((value in cell) x (Grand Total)) / ((Grand Row Total) x (Grand Column Total)). If we apply Index calculation on our example here is the result:
<telerik:PivotGridAggregateField Aggregate="Sum" DataField="Price">
<TotalFormat TotalFunction="Index" />
</telerik:PivotGridAggregateField>

PercentOf  values in the cells are percents of a sample  for example percent of next/previous or percent of a particular group description.

PercentOfGrandTotal  values in the cells are percent of the GrandTotal.

PercentOfColumnTotal  values in the cells are percent of the ColumnTotal.

PercentOfRowTotal  values in the cells are percent of the RowTotal.

RunningTotalsIn  the value in the cell is aggregation of the value in the previous cell and the total in the current one. Last item in the collection holds the GrandTotal values. For example in the image below the value which stands for "Pen" in promotion "Extra Discount" is a sum of its own total (32.67) and the value of "Notebook" in promotion "Extra Discount" (69.10).
<telerik:PivotGridAggregateField Aggregate="Sum" DataField="Price">
<TotalFormat TotalFunction="RunningTotalsIn" Axis="Rows" Level="0" />
</telerik:PivotGridAggregateField>
 PercentRunningTotalsIn  the value in each cell is accumulated from the total in it and the value in the previous cell. The result is presented as percent of the GrandTotal. GrandTotal is present in the last item in the collection with the value 100 percents.
<telerik:PivotGridAggregateField Aggregate="Sum" DataField="Price">
<TotalFormat TotalFunction="PercentRunningTotalsIn" Axis="Rows" Level="0" />
</telerik:PivotGridAggregateField>
 RankTotals  the value in the cell is integer representing the rank of the current total in the current collection of totals. You can set ranking to be from smallest to largest or from largest to smallest.
<telerik:PivotGridAggregateField Aggregate="Sum" DataField="Price">
<TotalFormat TotalFunction="RankTotals" Axis="Rows" Level="0" />
</telerik:PivotGridAggregateField>