How to combine data (categories) when making a pie chart?

Hi,

I have an Excel spreadsheet with several lines of everyday expenses, and I would like to use a pie chart (that represents spending by categories) for my monthly expenses as I go along. But for some reason, the categories (Food, Shopping, Gas/Fuel, etc) didn't combine and this is what I have got:

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And also, is there any formula or function that can automatically calculate the total expenses in each categories as I add new data (new expenses) onto the spreadsheet?

Attached is a copy of the Excel spreadsheet.

Thank you for your help in advance.