You can upgrade to Tally.ERP 9 Release 5.x and use lower versions of Tally.ERP 9, if required.
For example, Customer using Tally.ERP 9 Rel 4.93 or below, wants to upgrade to Release 5.0 in the same folder.
● Take data backup in existing Tally.ERP 9 release.
● Install Tally ERP 9 Release 5 in same folder where previous Tally.ERP 9 is running.
● Now nothing special you have to do you can use Release 5.0 and your data will automatically will work in this version.