Caching causing issues with Market Press cart pages

I have been using WP Super Cache on my WordPress site. We recently put up a small MarketPress shop. I’ve been having issues with cart pages not refreshing, refreshing and giving users a “no items in cart” message. Needless to say, my users are frustrated. I’ve done a lot of plugin disabling trying to figure it out, and it has come down to me having to disable WP Super Cache in order to appease users. I understand (or think I do anyway) thru some research here that this is because of full page caching. I’ve read a lot of the posts and have pretty much figured out that I need to disable that. My cart appears in the sidebar of (nearly) every page on my site. I am at a loss on how to proceed. Obviously, I do not want to keep caching turned off. Next thing is, users will be complaining about page load speed. I’d love some specific help on how to remedy the conflict with WP Super Cache and Market Press or… suggestions for a different cache that plays nicely.