Looping thru datatable and adding up rows per one column

This can't be that hard but I can't come up with a solution...

1. I have a datatable

Amount  LocId
------------  -------
1.00           STL
2.00           Laundry
4.00           STL
5.50           XYZ
9.00           STL
1.50           Laundry

2. This is what I want to do -->Add up the rows per "LocId" and insert into a table. So:

14.00      STL
3.5           Laundry
5.50         XYZ

3. I thought about looping and comparing LocId from one row to the next one. If same, add up. If not, move to the next row but then I think I have to do this for second row, third one, etc. Maybe somehow with LINQ?

Again, this can't be that hard.