Conditional sum function depending upon adjacent column

I'm having some real trouble with this. I'm trying to make a budget spreadsheet. I used the template. I have a pie chart fed by a short, general table (a few cells titled "entertainment", "food", "transportation", etc.) and a larger chart below with every transaction. What I'm trying to do is feed the upper table with conditional sums from the lower table. I can reference the other table easily by typing its name and the column I want, but I can't figure out how to sort by an alpha filter in an adjacent column.

So, in the bottom table column E is "size of purchase". Column D is "category of purchase". I want to feed a cell in the top table (say, B2, or "total monthly food expenses") with the sum of all purchase amounts in column E that are titled "food" in column D. I cannot figure it out. How do I sum up all cells in column E that are under the same word in column D?

Optimally I'd like to insert that I just spent $20 on whatever (food, transit, etc.) and have the chart add that to the running total and insert the new value (the previous sum + this purchase) of total transactions under whatever category (food, transit, etc.) in the upper table that feeds the pie chart.

Thanks.