Sales Tax/Affordable housing proposal

I voted for both my Mayor and my city council rep, both of whom are proposing a sales tax increase as a means of funding affordable housing programs. I am supportive of the idea of our city government injecting financial incentives to increase housing affordability, I just don't understand how they can justify using regressive taxes to do so. Poorer people spend more of their paycheck, ostensibly subjecting more of their paycheck toward this tax. Wealthier people tend to save more, subjecting less of their income to this tax. This is to help less wealthy people get houses, right?