Date / Time conversions

[Jewels]

I am trying to conver the minutes of the time field to
tenths of an hour. I cannot seem to make it work. I had
to seporate the hh and the mm into seporate text boxes to
make it work but this is cumbersom for my users to enter
in the time. Is there some way that I can combine my time
in the same box and still convert the minutes to tenths of
an hour?

Thanks for your help
Jewels