Round corners on sidebar?

I've been trying to wrap my head around this one. I've managed to get round corners on the top and bottom of the page, and on the various button graphics I've created, but the sidebar is still a sore spot for me. It's square. And I can't figure out how to get it round!

I'm using a graphic for the background in the sidebar, and I'm repeating it.

If I round the corners on this I'll end up with a scallop type of effect, and I don't want that.

My minds eye says force white round corner graphics into each corner, but I haven't got the foggiest how to do this.

http://strategicsense.ca is the site I'm playing with right now, in case you need that.

Thanks.

Velma