!default_rounded_amount ||= 5px

// Round corner at position by amount.
// values for position: "top-left", "top-right", "bottom-left", "bottom-right"
=round-corner(!position, !amount = !default_rounded_amount)
  border-#{!position}-radius= !amount
  -moz-border-#{!position}-radius= !amount
  -webkit-border-#{!position}-radius= !amount

// Round left corners by amount
=round-left-corners(!amount = !default_rounded_amount)
  +round-corner("top-left", !amount)
  +round-corner("bottom-left", !amount)

// Round right corners by amount
=round-right-corners(!amount = !default_rounded_amount)
  +round-corner("top-right", !amount)
  +round-corner("bottom-right", !amount)

// Round top corners by amount
=round-top-corners(!amount = !default_rounded_amount)
  +round-corner("top-left", !amount)
  +round-corner("top-right", !amount)

// Round bottom corners by amount
=round-bottom-corners(!amount = !default_rounded_amount)
  +round-corner("bottom-left", !amount)
  +round-corner("bottom-right", !amount)

// Round all corners by amount
=round-corners(!amount = !default_rounded_amount)
  border-radius: !amount
  -moz-border-radius= !amount
  -webkit-border-radius= !amount

https://gist.github.com/140430

SASS, not SCSS

Round Corners SASS

css

SASS