title: Ruby BigDecimal rounding
body: <p>I would like to round a BigDecimal to 2 decimal places, but when using the round method, it doesn't seem to double round:</p>
  
  <pre><code>BigDecimal.new('43382.0249').round(2).to_s('F').should == '43382.03'
  </code></pre>
  
  <p>But instead, I get output: 43382.02</p>
  
  <p>I've also tried all the other rounding modes available, <code>ROUND_UP</code> seems to do the job, but it screws up other rounding scenarios, e.g. '670.1541' becomes '670.16' (incorrect) instead of '670.15' (correct)</p>