Canada to US Taxes and Duties

Thank you everyone for helping out!

I’m making my first purchase for a handbag at a luxury retailer in Toronto, Canada and have no idea how the taxes/duties work?

They’re shipping it from Canada to California.

My total is $827 USD and saw there’s a rule where purchases under $800 are not subject to taxes.

The retailer can’t guarantee if I’ll have taxes/fees due however want to know how it works and if I am billed, about how much?

Will I have to pay the FedEx driver or am I invoiced separately?

Thank you so much!