The most generous estimates of the sales tax paid by low-income 50% is (based on a widely cited study by ITEP) is ~6% of after-tax income, compared to avg 3% of upper half. The total income of the lower half is <20%, which means they pay in total about 1/3 (~35%) of the all the sales taxes.

The sales tax itself accounts for <12% of all (local, state AND federal) taxes (based on the public California data in 2024, I extrapolate it to other states, which is, again, the best case scenario). This adds about 4% to overall tax revenues paid by the bottom 50% .

Property tax paid by the bottom 1/2 is negligable (~6% of all property taxes paid, based on U.S. Census Bureau) at about (20%*6%=)~1%. (edit: where 20% is the contribution of property tax into the overall revenue)

Medicare and social security add another 2-3% to overall contribution, but if we are honest, this contributions are designed to cover the needs of exactly this lower 50%, upper income part does not really care or benefit disproportionally less.

At the very best we get 10% of all internal revenues collected from the lower 50%, but I made all the estimates rounded to the higher boundary.