You don't need to register to collect sales taxes from customers in every state. You'll only collect sales taxes from customers who live in the states states where you have nexus!
"Nexus" is a physical presence that's significant enough for you to be required to comply with that state's sales tax laws.
You'll always have nexus in your home state where you are located. The most common causes for nexus in other states are:
We have more details about nexus here.
If you have nexus in a state, you would want to register for a license to begin collecting sales taxes from customers in that state.
If you are selling on Amazon, it's important to understand that FBA sellers could potentially have nexus with all of the states in which there are warehouses--if Amazon is storing your inventory in a warehouse in that state. That's because all those states say that your inventory counts as nexus.
TaxJar will automatically tell you where you have FBA nexus by adding the state to your account Dashboard with an Amazon badge next to the state name. We explain more about this feature here.