I have a degree in math and economics, and extensive Excel skills. I can perform this as a one-time-task, or produce a customizable system to allow for future analysis. Additionally, I have experience in retail grocery and IT with familiarity with SKUs and UPCs, and knowledge of the beer industry (although more in the Midwest than New England).
My impression is that you need to combine sales for different package sizes of a single product. If I have understood this correctly, I should be able to deliver this within a few days at the most.