ROLLUP
Applies to: 
Calculated column
Calculated table
Measure 
Visual calculation
Modifies the behavior of the SUMMARIZE function by adding rollup rows to the result on columns defined by the groupBy_columnName parameter. This function can only be used within a SUMMARIZE expression.
Syntax
ROLLUP ( <groupBy_columnName> [, <groupBy_columnName> [, … ] ] )
With SUMMARIZE,
SUMMARIZE(<table>, <groupBy_columnName>[, <groupBy_columnName>]…[, ROLLUP(<groupBy_columnName>[,< groupBy_columnName>…])][, <name>, <expression>]…)
Parameters
| Term | Definition |
|---|---|
| groupBy_columnName | The qualified name of an existing column or ROLLUPGROUP function to be used to create summary groups based on the values found in it. This parameter cannot be an expression. |
Return value
This function does not return a value. It only specifies the set of columns to be subtotaled.
Remarks
This function can only be used within a SUMMARIZE expression.
Example
See SUMMARIZE.