Sample Haml

.rounded_corners_test
  .rounded_top
  .rounded_right
  .rounded_bottom
  .rounded_left
  .rounded_top_right
  .rounded_bottom_right
  .rounded_bottom_left
  .rounded_top_left

Sample Sass

.rounded_corners_test
  background: #e5e5e5
  border: 1px solid #cacaca
  padding: 15px
  +rounded("3px")
  & > div
    background: #222
    height: 60px
    margin-bottom: 15px
    width: 100%
    &:last-child
      margin-bottom: 0
  .rounded_top
    +rounded_top("3px")
  .rounded_right
    +rounded_right("3px")
  .rounded_bottom
    +rounded_bottom("3px")
  .rounded_left
    +rounded_left("3px")
  .rounded_top_right
    +rounded_top_right("3px")
  .rounded_bottom_right
    +rounded_bottom_right("3px")
  .rounded_bottom_left
    +rounded_bottom_left("3px")
  .rounded_top_left
    +rounded_top_left("3px")