function roundAmount(n) {
  var s = "" + Math.round(n * 100) / 100
  var i = s.indexOf('.')
  if (i < 0) return s + ".00"
  var t = s.substring(0, i + 1) + 
     s.substring(i + 1, i + 3)
  if (i + 2 == s.length) t += "0"
  return t
}

function showUSPrice(auPrice){
  var convRate = 91.03
  var newPrice = (auPrice * convRate) / 100;
  var result = roundAmount(newPrice);
  
  document.write(result);
}