1. Take a backup from Tally 5.4 & place the backup on the Desktop.
2. Start Tally 7.2.
3. Click on F3 (cmp info) and chose the restore option.
4. Select the Tally 5.4 backup file from the Desktop.
5. During restore, Tally 7.2 will ask whether you want to convert (rewrite) the old data into 7.2. Click- Yes.
Hope that helps,
Kishore Thaakur