If you have the Prompt for backup when exiting box selected in your Initialization settings, Wintix will prompt you to back up when you close Wintix.
However, Wintix will only prompt to backup once per day.
If you backup in the morning, then make a lot of changes in the program during the day, or make lots of sales during the day, when closing Wintix at the end of the day, you will have to either remember to backup manually, or set a reminder elsewhere to backup.