html5 tinymce woes –what am I doing wrong?

I’ve spent a considerable amount of time building my theme to be as correct as possible to follow the html5 guidelines. Following html5doctor and a number of other authors has given me a pretty decent understanding of the setup.

The problem I am having is not with my theme but with wordpress. When I manually edit my articles to wrap images with <figure> and use figcaptions, for some reason tinymce is completely screwing up my code upon submit.

Could someone provide a link to some documentation on what I need to change in tinymce to get rid of this horrible behavior?

thanks.

*Yeah I know a lot of browsers don’t support html5 yet, but if the theme properly shims the template I have yet to see any problem in a browser. Basically as far as I can tell we’re ready for html5 now.