Interesting that they'd pay for it via something regressive like sales tax (maybe a bit less regressive because it doesn't include groceries, but still)
If you make food, housing, education and healthcare tax exempt, it’s not regressive at all.
Taxing anything at a flat rate without regard for a person's ability to pay is going to pretty much wind up as a regressive tax. Not saying this is good or bad, just that it is what it is.