@BigRedConsulting before Wayfair was enacted, I would agree with you. You put the state in, and the % sales tax for that state.
After Wayfair was enacted, a business is now required to collect and remit sales tax in any state where they have economic nexus -- not just physical presence. The rules for economic nexus vary from state to state, as do sales tax rates and regulations. The taxability of specific items varies from state to state. Some states have local taxes in addition to state taxes. For example, downloaded software is taxable in some states, but not in others. You can't just mark the item Non Taxable, because it is not true in every state.
Rather than researching every single state tax law, rate, jurisdictions and which items are taxable, as well as trying to keep them current, you can use software like Avalara which will automatically compute the sales tax based on the most up-to-date laws and rates.
