Custom Report users are allowed to turn on/off totals in tables and pivot tables.
For tables the setting is on the measures. Clicking on the sum-icon Σ will activate/deactivate the total for that measure (Figure 1).
Figure 1: Table Total
In pivot tables the setting is found on the dimensions but works in the same way (Figure 2).
Figure 2: Pivot Table
Note! When using a table as a data source, the option needs to be made available by setting the totals should be active in the master item. This allows the developer to decide where it makes sense to allow totals.