The federal income tax has a strongly progressive structure. State retail sales taxes are strongly regressive. Social Security taxes are moderately regressive. How does it all add up? Well, the Center on Budget and Policy Priorities has this chart, which they say shows the overall tax system is "only moderately progressive."
I'd put it differently. The overall tax system is pretty progressive but seems to be built for a different era before the divergence of the 1 percent and the 0.01 percent from the 99 percent and the 99.99 percent. It rightly draws a large distinction between the bottom quintile and the fourth quintile but fails to draw a major distinction for gaps within the top quintile.