Hello.
First of all we need to know where do you have a wrong datetime ? At the Cash station(just a computer) or at Cash Register(fiscal registration,may be a printer with EKLZ )
If it's just a station ,you may fix your datetime at BIOS or by typeing NET TIME \\COMPUTERNAME /SET /YES for automatic time synchronize with PC .Warning ! PC Must be wth OS: WinXP ! Windows Vista or 7 DOESN'T SUPPORT this method !
if you have a fiscal register that connects to yours cash station and it's like Shtrih, then you may type at autoexec.bat setftime command .Example: Setftime 30 1 (For ANY FR by Shtrih-M )
Best regards