Compare, Merge, Sum & Delete Duplicates

I have the following data in Excel 2003:

Time Price Vol Type
8:58:19 2.77 5,000 Buy Up
8:58:19 2.77 3,000 Buy Up
9:00:00 2.76 10,000 Sell Down
9:00:02 2.76 1,000 Sell Down
9:00:02 2.76 1,000 Sell Down
9:00:02 2.76 5,000 Sell Down
9:01:11 2.75 3,000 Sell Down

I would like to merge rows with same "Time" column AND "Type" column, and then add the "Vol" column values, so that the end result becomes the following:

Time Price Vol Type
8:58:19 2.77 8,000 Buy Up
9:00:00 2.76 10,000 Sell Down
9:00:02 2.76 7,000 Sell Down
9:01:11 2.75 3,000 Sell Down

Appreciate if someone can offer some advice.

Thank you.