Here's an idea to clear up this mess nicely: get rid of all sales taxes. They're extremely regressive and complicate and impede commerce. Increase income, property, and capital gains taxes to compensate.
I agree sales taxes can be harder on the poor in some cases but it's a manageable risk. Blanket statements suchas yours do little more than expose the lack of depth of your understanding. They're only harmful if you assume sales tax is charged on the basics of life. Food, for example, is not taxable in many states. There's no reason the poor shouldn't pay sales tax on a television, however, or a car.
There are ways to make the taxes more fair overall. I'm a fan of the Fair Tax myself which offers a rebate up front every year to everyone that covers the tax paid for everyone up to the income level for poverty. That way nobody pays anything out of pocket until you make more than that base level. I also like that it wouldn't tax used goods. There may be other issues with the Fair Tax that I don't recognize as I am not an expert in the field but that method would seem to work well.
Anyhow, saying a regressive tax is inherently bad ignores that other forms of taxes are too easy to avoid for those wealthy enough to pay accountants and attorneys to do so. How's that any more fair?