Rounding a time calculation

I'm trying to make my service ticket that i created round our times in and out to the nearest .25 of an hour.

Here is what i have for the time calculation-

// determine the current row number

var ourName = event.target.name;

var matches = ourName.match(/.*(\d+)$/);

var rowNum = matches[1];

handleRow("h:MM tt", "StartTime", "StopTime", "BreakTime", "Overtime", rowNum);

But as of now it calculates just 1.34, 2.89. I want it to round down and up. So if its .12 hours round down to .00 and it if its .38 to round to .5 and so on.