I am not even sure if this is possible, but I figured I would ask the experts.

I would like a tool for my managers to use to assist them in paying their
employees correctly, however we have shift differential rules that make it
confusing.

The sheet would have a Time in and Time Out column (let's say A & B)
The sheet would then need to calculate the total length of the shift (Column
C)

Now for the tricky part...
Based on the length of the shift - a certain fixed number determines the
majority of the shift -
if the shift is at least 6 hours, but less than 8, then 4 hours
If at least 8 hours, but less than 10, then 5 hours

Then with that "majority number in mind", they would have to work that many
hours after 1500 (3 o'clock) - so we know to may shift differential for the
entire shift

For example

0900-1800 - Total time is 9 hours (so 5 determines the majority). Since the
employee did not work 5 hours from 1500, then the entire pay will be 1st shift

1100-1800 - Total time is 7 hours ( so 4 hours determines the majority).
Since the employee worked 4 hours in 2nd shift (after 1500), then the entire
shift will be paid 2nd

Like I said, this may not even be possible, but I figured it would be worth
a shot!

Thanks ahead of time