Crystal Reports - Time display formula field

Project Description:
I'm wanting to add a formula field (I'm guessing) that will print a "Promise Time" on our work order. This would be calculated by adding the PrintTime field and database field in the report
rolines.Time.

I will tell you what I know the best I can. The rolines.Time field duplicates on the work order for each service we perform and it is displayed as a fraction of the hours it takes for each service. For example: We
have an alignment on the workorder it will print 0.73 (roughly 45 min) next to the description for alignment. Now say we have an alignment and tire rotation it would print 0.73 next to the alignment and 0.20 (12 min) next to the tire rotation.

So what I want to do is ADD all of the
rolines.Time fields together and then ADD them to the current time so that the result will be a "promise time" or the time the work order should be complete. I would like to round up the result to the nearest 0 or 5 so that it will be easier for the tech to plan completion, such as a
result of 2:43 PM would be rounded to 2:45 PM And finally I want to add 10 min to the result to allow for office paper shuffling before the tech receives the workorder so the time is realistic to the tech. So the final result would be 2:55 PM