Please note if you use Taxjar they are the ones who determine the tax rate based on delivery address, ship from address, your Nexus set up in your TaxJar account etc.
Delivery address can be the customer's address, or contracts can have a specific delivery address.
Ship from address can be the store address in store setup, or you can use a dealers address as a delivery address for a contract.
Below are some links you can use to verify tax rate info.
Note the page below does not use a delivery from, so it is not always correct. Some states base tax rate on ship from address (Origin based sales tax states), some are destination based (based on delivery address). Where you have Nexus also affects how tax is calculated in some states.
The page below has a place to enter a from and to address, but it is not as easy to use as the page above, but will have the most accurate info, the only thing it doesn't take into account is Nexus. When you use Taxjar through RTO Pro Taxjar uses all info available to get the correct tax info.
If Taxjar is generating tax info you believe is incorrect contact Taxjar for more details.