Sum values depending on values in other fields

Hi! I am trying to create an invoice form that will hold varying VAT tax percentages. Each row has both a total price before tax (Field A), and a number indicating the VAT % of that row (Field 1).

I would like to show the total sums for three different tax levels on the bottom of my form, where each field would preferably autopopulate with the sums for that tax %.

For example: Fields A, B, D, and G should be summed because fields 1, 2, 4, and 7 show the same number, while fields C, E, and F sum because fields 3, 5, and 6 show the same number.

I am not super familiar with javascript but assume I will need to use a hefty amount of if statements.

I've looked at this thread to try to figure it out but need some help figuring out how to code it for acrobat: https://stackoverflow.com/questions/50879417/sum-field-values-based-on-condition-in-another-field-in-javascript

I'm working directly in Acrobat, right clicking fields > properties > custom calculation script.

Would love to hear if anyone has tips!