Roll-up without Subtotals

Rollup usually will show subtotals on every difference in the group. To show only a grand total, add 'grouping sets' and a '1' as shown below:

SELECT deptno 
     , job 
     , SUM(sal) 
  FROM emp 
 WHERE deptno <> 10                  -- narrow down this example 
   AND job IN ( 'MANAGER', 'CLERK' ) -- narrow down this example 
 GROUP BY grouping sets ( ( deptno, job ) -- One row for every distinct combination of these 
                          , 1             -- Grand total super-aggregate 
                        ); 

DEPTNO	JOB	SUM(SAL)
30	CLERK	950
20	CLERK	1900
20	MANAGER	2975
30	MANAGER	2850
		8675

Or you can add 'Total' to it by decoding the 1st column. The Grouping value is 1 when it's a total.

SELECT DECODE(
              GROUPING(deptno) -- Decode the GROUPING value for DeptNo
             ,1                -- If it is 1,
             ,'Total'          -- Then print 'Total'
             ,deptno           -- otherwise, print the actual DeptNo
             ) AS dept         -- call this column 'Dept_Tot'
     , job
     , SUM(sal)
  FROM scott.emp
 WHERE deptno <> 10                  -- narrow down this example
   AND job IN ( 'MANAGER', 'CLERK' ) -- narrow down this example
 GROUP BY grouping sets ( ( deptno, job ) -- One row for every distinct combination of these
                          , 1             -- Grand total super-aggregate
                        );

DEPT	JOB	SUM(SAL)
30	CLERK	950
20	CLERK	1900
20	MANAGER	2975
30	MANAGER	2850
Total		8675