How to separate business & personal items from grocery receipts?

I'm a cottage food baker & fairly new to it so I'm filing taxes based on last year. I didn't realize I should've kept personal grocery items & baking items separate purchases or this would be a lot easier on me!

How do I go about separating my personal items from receipts to enter the amount of what I actually use to bake with in the deductions for my taxes?

Will adding up the cost of each item be enough? Do I need to find the sales tax of each item & add that in as well?