решение без jQuery
<body>
<div id="discount_cal">
<input name="discount" type="radio" checked value="1">Без скидки |
<input name="discount" type="radio" value="5">5% скидка |
<input name="discount" type="radio" value="10">10% скидка |
<input name="discount" type="radio" value="20">20% скидка |
<input name="discount" type="radio" value="30">30% скидка</div>
<script>
discount_cal.onclick = function (e) {
e = e || window.event;
target = e.target || e.srcElement;
if (target.tagName != "INPUT") return;
alert(target.value);
}
</script>
</body>