    </p>
    <p>
      if <code>rounding_mode</code> is omitted, or is <code>null</code> or
      undefined, the current
      <a href='#rounding-mode'><code>ROUNDING_MODE</code></a> setting is used.
    </p>
    <p>
      See <a href='#Errors'>Errors</a> for the treatment of other
      non-integer or out of range <code>decimal_places</code> or 
      <code>rounding_mode</code> values.
    </p>
    <pre>
x = 1234.56
Math.round(x)                             // 1235

y = new BigNumber(x)
y.round()          