Hi @Nanasbest,
You only need to collect sales tax from buyers in states where you have a significant connection. See number two on this article for more about sales tax and what qualifies as a nexus.
If you determine that you do have a significant connection, in the items > taxes section in your Square Dashboard, you can create taxes, such as CA Sales tax, and assign it to locations that you want the tax to be charged. Here is more on creating taxes from Square.
If you are collecting taxes for your Square Online Store, there is an automatic tax calculator that you can use. Here is more about how to use the automatic tax calculator for states. It's under Settings > Taxes on your Online Store Dashboard and you check the automatically calculate taxes box when selecting the United States as your country.
Note: Tax settings from your Square account do not sync to your Online Store. You’ll need to set up taxes specifically for online purchases in Settings > Taxes.
