Please help macro guru's

I have numerous sets of volumes that are recorded from a pump. I am trying
to write a macro to totalize the volumes for each set in column B to to get a
total volume in column C. I can manually do this in excel buit want a macro
as I have hundreds to totalize.
See how the total volume in column C at the Set1 row becomes the cell above
the Set1 statment in column C plus the volume in column B at the Set1
statment row. Each value for the set 1 total volume is the next volume in
column B plus that last volume in Column C (that was the end of Set 0). My
problem is I can't figure out how to lock the value in column C above each
new set statement and have all cells in B added to it outputting in column C.
Of tricky note is that the numbers in column B and the set statements that
go with them are not uniform in number and size and that a set can have more
or less volume(e.g more or less columns)


A B C
Volume Total Volume
2423.616211 2423.616211
2423.758301 2423.758301
2423.900635 2423.900635
2424.042725 2424.042725
Set1 1.504936337 2425.547661
1.955039501 2425.997764
2.405142546 2426.447867
5.072114468 2429.114839
7.739086151 2431.781811
10.40605831 2434.448783
13.07302952 2437.115754
Set2 4.737580776 2441.853335
9.475161552 2446.590916
14.21274281 2451.328497
18.9503231 2456.066077
23.68790436 2460.803658
28.42548561 2465.54124



Thank you
Ben