Rounded corners of rectangle with UniformToFill ImageFill inside

How-to Discussions
1

I need just multisize image with rounded corners. Perfect works like this:

<Rectangle 
  Margin="0,0,0,10" 
  CornerRadius="5"
>
  <Image
    Url="{url}"
    StretchMode="UniformToFill"
   />
</Rectangle>

But this one have no rounded corners. I understand that i need to use ImageFill, but in this case image doesnt show. I read about Mask, but i think i can’t use it for multisize images. Any idea?