If Statment for categorizing

I have a list of banking transactions. I want to categorize each into, for example, retail, gas, fast food, etc… My thoughts were to simply have a cell at the end of the transaction row to then place a letter in it to categorize that row. Could an if statement add all of the “A” and add them all up, and also do that for the “b”, etc…?

Example:

A B C D
1 June/07 Staples $10.50 “A”

2 June/07 Pizza $15.00 “B”

3 June/07 Walmart $36.50 “A”

Etc…

“B” “A”
Fast Food Retail
$15.00 $47.00
(If statement added all of the values in column “C” that were categorized in “A” and “B”.

What is the IF Statement formula if there is one?