title: rounding in a tuple
body: <p>I wrote the following code:</p>
  
  <pre><code>for value in values:
      p = round(stats[value] / stats.sum(),2)
      e = round(-p * math.log(p,2),2)
      print (e)
      plist.append((value,p,e))
  </code></pre>
  
  <p>the "print(e)" displays the values 0.46 and 0.53. That's what's expected.
  When I print the list, I obtain the following:</p>
  
  <pre><code>[('Y', 0.57999999999999996, 0.46000000000000002), 
   ('N', 0.41999999999999998, 0.53000000000000003)]
  </code></pre>
  
  <p>the value of 'e' that was rounded properly, is now appended to the list as 0.46000000000000002 and 0.53000000000000003.</p>
  
  <p>Why is that and how can I get the rounded values on 2 decimals in my tuple ?</p>