I'm curious, how many Australian websites force you to enter your shipping address before you shop? In the US to properly account for sales tax you basically have to get the coordinates of the address you're shipping to.
The most degenerate example I'm aware of, is that my boss lives on a county border. On the other side of his street, sales taxes are 7.5%. His are 9%. The zip code, city (kind of - technically one side is part of another city, but the post office recognizes it as the same city), and street name is all the same, but the county is different, which you don't collect for shipping reasons.
Every online retailer I've seen collects it wrong, including Amazon, although maybe their backend for reporting purposes calculates it right. When searching for software solutions to sales tax, most of them seem to get it wrong too.
The most degenerate example I'm aware of, is that my boss lives on a county border. On the other side of his street, sales taxes are 7.5%. His are 9%. The zip code, city (kind of - technically one side is part of another city, but the post office recognizes it as the same city), and street name is all the same, but the county is different, which you don't collect for shipping reasons.
Every online retailer I've seen collects it wrong, including Amazon, although maybe their backend for reporting purposes calculates it right. When searching for software solutions to sales tax, most of them seem to get it wrong too.