This is Brendan from the Shopify Support team.
Generally speaking, you're not required to collect taxes from customers outside of your home state unless you have "Nexus", or business operations in another location.
For international and out of state orders, your customers won't be subject to sales tax, just the orders placed within your home state. Shopify does collect taxes for these orders automatically based on the zip code you enter in the Settings > Taxes section of your Shopify Admin.
Does this help? If you have more questions please let me know.
I am really confused. I understand the nexus. However, when I applied for my Business Number with Canada, they made it clear that I was supposed to remit taxes to them as a US business for anything sold to Canadians once my worldwide sales are over $30k.
So are we supposed to charge or not because at this point I am really really confused...