Running Total in Query

[RizMomin]

I need some help to create a Column in Query which will give me
Running Total. Let me explain you what i have:
I have a Invoice # and Invoice Total ($) field in the query.
Inv # Inv Total ($)
1001 $ 301.00
1002 $ 200.00
1003 $100.00

I need the 3rd column with following answer:

1001 $301.00 $301.00
1002 $200.00 $501.00
1003 $100.00 $601.00

Help is appreciated in advance...

 

[MacDermott]

This is easily achieved in a report, but not in the query itself.