My 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

```

Output:

```
  sam@sam:~/code/python$ ./t2.py
  1.6
  1.55
  1.56
  sam@sam:~/code/python$

```

`round(1.555, 1)` outputs `1.6`.

Why doesn't `round(1.555, 2)` output `1.56`?