creating text specific formulas in excel

I have a page setup similar to that of a checkbook register. Date/Description/Debit/Credit/Balance. I need to get a total for a specific field entered in the Description column that is listed multiple times.
ex.
Merl’s Plumbing -$27.00
Jake’s Shoes -$50.00
Merl’s Plumbing -$15.45

I only want a total for Merl’s Plumbing.