title: Rounding a number to 2 decimal places fails
body: <p>I have a nasty bug in an interest rate calculation: I have to round the answer to the nearest cent, but</p>
  
  <pre><code>interest = Math.round(interest * 100) / 100;
  </code></pre>
  
  <p>removes the entire decimal portion. <code>interest</code> is a <code>double</code> type. Why is this? The equivalent code works fine in C++.</p>