To the best of our knowledge there is no particular standard for retaining bankruptcy records.  In fact, I think an argument can be made that they are not even the Treasurer’s records since they originate from a Federal Court (although there might be items in your file that are not court issued documents).  Additionally, in this age of electronic filing, the court documents are readily available for download if the need should ever arise.  So I think an argument can be made that the court documents need not be retained by the Treasurer.

That being said, the Library of Virginia requires that the lists of taxes written off (including those discharged in bankruptcy) be kept for 3 years or until audit.  Therefore it is certainly prudent to retain your bankruptcy file for this period as well as it embodies the documentation of the discharged taxes on the list.