Combo box to list numbers for OT tracking

[vad77]

I am currently creating a databasse to track OT hours for my department. I want to create a combo box to select the number of hours to be posted so the hours are consistant. Some users might enter 1.30 for an hour and a half instead of 1.5. So I want to create a combo box that has the hours in the following format: 1.0, 1.25, 1.50, 1.75. 2.0 and son on. Is there an easy way in somekind of VBA coding to achieve this or o I have to build a list?
Looking forward to your responses.

[orange]

You could have users identify their StartTime and EndTime on a Form; subtract StartTime from EndTime to get the length/duration.
This seems only a small piece of a Pay and Benefits System or HR System or Finance System. Do you have a good understanding of how your piece "fits" with the larger system(s). Just saying you could be building an island....

[vad77]

Thia is just a stand alone db with no ties to any other system. It's just to keep track of Ot and send bi-weekly reports to the directors. The OT is just reported in hours worked no start and stop times are recorded.