Some DAX snippets for % of Grand Total

PowerBI-PercentOfGrandTotal

//Single measure version
% of Total = DIVIDE(SUM('Sales'[Revenue]), CALCULATE(SUM('Sales'[Revenue]), ALLSELECTED('Product'[Category])))

//As traced in Power BI Quick Calc "% of Grand Total"
EVALUATE
  TOPN(
    1001,
    SUMMARIZECOLUMNS(
      'Product'[Category],
      "M0", CALCULATE(
        DIVIDE(SUM('Sales'[Revenue]), CALCULATE(SUM('Sales'[Revenue]), ALLSELECTED('Product'[Category])))
      )
    ),
    'Product'[Category],
    1
  )

ORDER BY
  'Product'[Category]