How do I create a SQL SELECT to give me totals on a level break example order number?

I have searched around and found the group by grouping sets, but that
requires me to summarise data which is not what I want to do.

I need to list all records in the file for say PO number. At the end of the
PO number, I need it to give a subtotal of quantities,

Example:
Select * from lib.file
group by grouping sets (PONUM)

This does not work for me.

What I would like to see is

PO Number line Vendor Cost
1234 1 abc 10.00
1234 2 abc 12.00
Vendor Total 22.00

1235 1 def 5.00
1235 2 def 12.00
Vendor Total 17.00

Company Total 29.00


TIA, Darryl Freinkel.