title: Pandas: Timestamp index rounding to the nearest 5th minute
body: <p>I have a <code>df</code> with the usual timestamps as an index:</p>
  
  <pre><code>    2011-04-01 09:30:00
      2011-04-01 09:30:10
      ...
      2011-04-01 09:36:20
      ...
      2011-04-01 09:37:30
  </code></pre>
  
  <p>How can I create a column to this dataframe with the same timestamp but rounded to the nearest 5th minute interval? Like this:</p>
  
  <pre><code>    index                 new_col
      2011-04-01 09:30:00   2011-04-01 09:35:00        
      2011-04-01 09:30:10   2011-04-01 09:35:00
      2011-04-01 09:36:20   2011-04-01 09:40:00
      2011-04-01 09:37:30   2011-04-01 09:40:00
  </code></pre>