Cache control for HTML5

Basically I don't want caching but the cache control meta tag doesn't validate in html5, is their a new way of disabling caching?

Or should I just ignore the fact that it doesn't validate, I don't always see the big deal with validation, if I was using a mix of /> and > end tags then I understand the problem but in this situations like this I don't see how the meta tag would conflict with the html5.