Does ie 9 really support CSS rounded corners?

Recently, we have been testing a large menu for sharepoint2010. We are looking forward to the effect of CSS rounded corners because we focus on the UI. I was prepared to write a general idea. I packed a layer of webpart content, and I could set the surrounding image and the image of the webpart title at will. Then I gave up on css3. Today, when I heard a brother in the group say that ie9 also supports HTML5, I asked if CSS rounded corners are supported. As a result, I quickly got an ie9 RC, after reading the demo on the website, I felt that it was okay. So I modified the CSS and the result was disappointing. The border effect was still not rounded. I thought it was a CSS error. When I looked at it, I copied the demo on the ie9 website.Code. In desperation, another Google browser was launched. Unfortunately, the same CSS code can perfectly display rounded corners in chrome, and ie9 is not working!