Sales tax is collected in 45/50 states, and your obligations are based on whether you have a physical or economic nexus in any given state (each has its own set of laws/requirements).
Check out TaxJar's state by state guide to get some idea of what you might be facing at https://www.taxjar.com/states/
Best recommendation is to consult with an expert on tax compliance to ensure you stay within the laws.
Hey @Akrutiartz ,
I second @BobsMojo's suggestion to consult a professional. Since you're in Canada, you have access to the Canada Revenue Agency's Liaison Officer service. It's a free service, and you'll be speaking to some of the most knowledgeable people in Canadian taxes. If you get a chatty guy like I did, you can get some very fun stories, too!
When we first started Intuitive Shipping Inc., I had a 2-hour meeting with a fantastic gentleman from the service. He answered all of my questions and really set us up in the right direction to ensure compliance. Our accountant echoed the exact same advice the liaison did and also noted we saved money from not having to spend so much time asking him questions or fixing our mistakes.
I hope this helps with your expansion into the States!