Excel 2010 :: How To Aggregate Data From One Column

I am using Excel 2010.

I have a large spreadsheet with brands and volumes.

Many of the brands run the same processes, so I can consider them as one.

For example:

Brands - Volumes

A--------10
B--------16
C--------18
D--------20
E--------16

Imagine that A and C are basically the same. So the value that I really care about it (10 + 18) = 28
B and D are the same, so I care about (16+20) = 36

The output I need is:

A&C - 28
B&D - 36
E --- 16

Can I use SUMIF to basically say: Sum this IF =A OR or =B ?

Can I apply an IF function with concatenate to merge the A's with C's and B'd with D's?

The spreadsheet is large and this process will apply to many different groups of brands.