Solution : https://service.sap.com/sap/support/notes/381809 (SAP Service marketplace login required)
Key words : 
additional key words ff 747, incorrect posting key, rounding difference comparison, individual check, xauto flag, solution implement, attached correction, correction, description, note 366024
Related Notes : 
       
| 437983 | No FI transfer in case of tax rounding differences | 
| 428095 | FF753 in case of pure tax docs with rounding differences | 
| 425022 | Tax line items not summarized correctly in FI interface | 
| 366024 | Error FF747 due to rounding difference comparison |