How Do I know if I need to charge sales tax for a customer purchasing out of state

[Limitless4x4]

How do I know if I need to charge sales tax when a customer is purchasing from out of state?

On my website when a customer purchases something from there depending on where they live it sometimes charges tax and sometimes does not

[Minion]

Generally with onlines sales, sales tax is only collected from customers if you have a physical location in that same state.