Why python round so strange?
<p>My code:</p>

<pre><code>  #!/usr/bin/python
  # -*- coding: utf-8 -*-
  print (round(1.555,1))  #It seems normal
  print (round(1.555,2))  #Why it is not output 1.56?
  print (round(1.556,2))  #It seems normal
</code></pre>

<p>Output:</p>

<pre><code>  sam@sam:~/code/python$ ./t2.py 
  1.6
  1.55
  1.56
  sam@sam:~/code/python$
</code></pre>

<p>round(1.555,1) is output 1.6 .</p>

<p>Why round(1.555,2) is not output 1.56?</p>

<p>Thank you~</p>
