Help to calculate Commulative %

Hi Anonymous ,

What connection mode data source your report is connected to? I saw you mention that you can't create additional tables in DM, is the data source in DQ or LC connection mode? Or are you unable to create additional tables in DM for some other reason?

I have created an sample pbix file(see attachment), please check if it is what you want.
1. Create a calculated column to get the index base on Root Category and Category fields (It is necessary for the cumulative calculation later, use it as a base column for the cumulative calculation)

Index = RANKX ( 'Table', 'Table'[Category],, ASC, DENSE )

2. Create two measures to get the cumulative value and cumulative percentage respectively

Cumulative Total = 
VAR _tab =
    SUMMARIZE (
        'Table',
        'Table'[Root Category],
        'Table'[Category],
        "@sumofid",
            CALCULATE (
                SUM ( 'Table'[ID] ),
                FILTER (
                    ALLEXCEPT('Table','Table'[Root Category]),
                    'Table'[Index] <= SELECTEDVALUE ( 'Table'[Index] )
                )
            )
    )
RETURN
    MAXX ( _tab, [@sumofid] )

Cumulative Percentage = 
DIVIDE (
    [Cumulative Total],
    CALCULATE ( SUM ( 'Table'[ID] ), ALLEXCEPT ( 'Table', 'Table'[Root Category] ) ),
    0
)

Best Regards