Extracting Shift Differentials from Hours Worked.

Hi,

I have created a payroll sheet to compare to my company payroll sheet. The sheet works well in its current form but I would like to streamline the time entry process. We have several different shift differentials. Currently I account for the differentials by entering them manually into the time sheet. I then have if statements which point to particular cells on the time sheet to determine whether a differential should be paid. I would like to automate that process. I would like to just enter my actual punches i.e. (Time in, Time out,). This is a total of four punches per day. From that I would like to find and them sum the differentials.

The differentials are as follows:

Weekdays
5:30 PM - 10:59 PM = Base Rate + 5%
11:00 PM - 6:59 AM = Base Rate + 10%

Weekends
5:30 PM - 10:59 PM = Base Rate + 10%
11:00 PM - 6:59 AM = Base Rate + 15%

I am really stuck on how to do this. I have been knocking my head against the wall for a while now. Thanks for any help you can provide.
Please see the attached workbook.