Tax Calculation on Budget Sheet

Hi there, I'm looking for some help with creating a budget sheet that adds specific taxes to specific items.

I'm trying to make it work so that I have a column for taxes, GST & PST (two different taxes).

I would like it to be able to write G for GST (5%), P for PST (7%) and GP (13%) for both and have the taxes calculated in a separate column.

I've tried a couple of different ways to get this to work but can't seem to make it happen...

Here is an example of the sheet: