Yes, of course, random banner “rotation” is possible in OpenX; however, most people think of a banner rotator program as one where you can specify the order of banner rotation. OpenX doesn’t do this, and this is why I have said that OpenX is not a “banner rotator”, but rather, OpenX is a banner delivery system.

Simply put the banners of the campaign and use the iframe invocation code for the Zone ,set the rotation interval here.

Refer:
http://www.openx.org/en/faq/how-can-i-rotate-ads-every-specified-time-frame-without-reloading-page