SELECT NULL AS pracID, NULL AS klientID, SUM(TotalDue) AS Suma
FROM Sales.SalesOrderHeader

UNION ALL
SELECT NULL, CustomerID, SUM(TotalDue)
FROM Sales.SalesOrderHeader
GROUP BY CustomerID

UNION ALL
SELECT SalesPersonID, NULL, SUM(TotalDue)
FROM Sales.SalesOrderHeader
GROUP BY SalesPersonID

UNION ALL
SELECT SalesPersonID, CustomerID, SUM(TotalDue)
FROM Sales.SalesOrderHeader
GROUP BY SalesPersonID, CustomerID
ORDER BY 1