If I have a spreadsheet with various data in a column (perhaps sales rep
names) and I want to sum all values associated with that sales rep, how do I
do it.

For example, if I have hundreds of clients assigned to either sales rep A,
B, C, D or E and I want to know the dollar value of sales for each sales rep,
what is the proper formula? I would separate totals for the sales dollars
where sales rep = A, sales rep = B, on so on.