"To reiterate something that has already been mentioned several times here, corporations (like Line 6) don't charge sales tax. Governments do. ANY price advertised by a U.S. corporation is pre-tax, and the corporations has no control over the sales tax that may be charged by the purchaser's local government."
This strikes me as a strange point to make...
US corporations sometimes can and do charge sales tax. This thread is specifically talking about the sales tax section on the Line 6 checkout. Corporations just don't get to keep the money they charge. It Its not like foreign governments are magically siphoning money from corporate checkouts systems before the money enters the corporate account. Its true that the governments set the amount extra to be charged but this is certainly not what I what I was complaining about.
I'm a developer of a UK based E-commerce website and here It's normal for retailers to set the price of consumer products such that the advertised price includes tax and where it doesn't or can't its usually stated. What you see is what you pay. Our prices include tax, uk based or otherwise, where we charge it.
It would seem like this isn't common practice in the US which explains what happened but isn't particularly satisfying as it feels like a bit of a bait and switch tactic given the end result