So I searched for an app to no avail for the following issue.
We sell a product that has very specific taxes that need to be added at checkout. For example, Wine is taxed $.50/bottle in California but $.10/mL in Texas (wholesale prices). So the product price would be normal, but then depending on where the shipping zipcode is further taxes would be automatically calculated and then charged at checkout. This would be in the form of individual lines showing all the taxes.
So for a bottle of Wine in California it would show
Product Price - $29.99
Sales Tax - $2.17
Custom Bottle Tax 1 - $0.50
etc etc
In theory this seems straightforward as you’re just running calculations based on the numbers we supply for however many products, but I couldn’t find an app that does this to any degree.