Hi Chester,
i think you need to elaborate more on your requirement.
for my understanding you can follow the process to create that report.
After create the report design, you need to create a parameter.
You need to pass the value of login date time (currentdatetime) to the formula "start time" and then create a formula like "dateadd('H',+8, {@start time)" as the name "End time".
In the report selection formula create the below formula...
timefield > start time and timefield < end time
then the report will display the total sales for the shift...
Hope this information will help you...
Thanks & regards,
Naga.