I specifically covered that in my comment, which seemed to be ignored. As stated the proportion of the tax (like sales tax and vat) should be adjusted based on how much of a luxury something is. Food and essentials are tax free, diamond rings and luxury cars are high taxed, etc.
Therefore no it is **not** a regressive tax, people who can only afford essentials live tax free, and those who waste their money on luxury are heavily taxed, something the poor cant do (and should avoid at all costs).
Since being rich should not be penalized, but wasting and destroying wealth should be, this is exactly the reason why I support such taxes.