Need to have images in your out of the box SharePoint web parts rounded as shown below? You can use image rounding web part for that.
Simply add image rounding web part to your page from the web part list:
While in page edit mode, this web part will allow you to control the image radius from web part properties:
When ready, save the page and see all of your images rounded with desired radius.
You only need one web part per page and all of your images on that page will be rounded.