How to I add missing Rounding Mode options

If any of the rounding modes are not available, you will need to add them to object Absence Accrual Rule.

Navigate to Setup, App Setup, Create Objects

Select the object Absence Accrual Rule

Scroll to the custom field Rounding Mode and select the hyperlink

Scroll to the Values section and select the New button

Enter the name of the missing Rounding Mode, e.g. Floor, select Save

For details on rounding vacation totals please read the Rounding mini guide.