Hourly pay rate for teachers/TA

How is this calculated ? Does your school/district round off the minutes worked if you are paid hourly? For eg: if you work from 10 am to 2.21 pm, it is calculated as 4.36 work hours ( 21 out of 60 minutes is equivalent to 36/100) . The .36 is rounded off to .25 and paid accordingly. So makes it look like you worked a total of 4 hrs and 15 minutes only.