I have no idea how business sales were affected, but the shutdown was pretty intense from what I've heard.
I helped shut down downtown Washington, DC in September 2002. In that case, businesses were significantly affected. I know this for a fact because I worked in downtown DC and the amount of traffic and pedestrians on the streets during our weekday protest was like a weekend.
It helped that the police scared lots of people into staying at home and others came in later in the morning.
Chuck