Number Step Input

Not working if number is whole number.

HTML

<html>
<head>
</head>
<body>
    <input id="test_input" type="text" step="0.01">
</body>
</html>

JavaScript

document.getElementById("test_input").onchange = function() {myFunction()};


function myFunction() {
  document.getElementById("test_input").value=       parseFloat(document.getElementById("test_input").value).toFixed(2);
}