Excel 2007 : Overtime Calculation Formula Help Excel 2007, Rounding Function help

I need help with a formula in a time sheet.

A1 is Start time
B1 is Lunch Out
C1 is Back From Lunch
D1 is End of Day

E1 is number of hours worked taking into account for lunch period.
this is the formula used - =((D1-A1+(D1<A1))-(C1-B1+C1<B1)))*24

F1 is the number of hours worked credited with time and a half calculated for all time over
eight hours, here is the formula used - =IF(E1>8,E1-8)*1.5+8

The formula in F1 correctly calculates when E1 is higher than 8 hours.

The problem is that if someone works less than 8 hours, F1 displays 8 hours and not a
lesser number of the lesser hours worked.

Any suggestions how to make the calculation and display in F1 the hours less than 8?

Any suggestions to make F1 round to the closest quarter hour in the same formula?

Any and all help is GREATLY appreciated!