There's two ways you can do it.
1. If you use the command line, after you transfer to / from the floppy. Type 'sync' that will sync all of the data.
2. If you want it to immediately copy the data every time you use the floppy drive, edit your /etc/fstab file, for the floppy (fd0) add the sync command.
Something like this.....
/dev/fd0 /mnt/floppy auto noauto,owner,kudzu,sync 0 0
The sync option there near the end will automatically make the files you copy immediately write.