Here you can see the digital way of telling the time, more common in America. Compare the digital and the analogic systems under the Explanations tab.

          DIGITAL  =  ANALOGIC

4:00 - 4 o'clock = 4 o'clock
4:05 - four o five = 5 past 4
4:10 - four ten = 10 past 4
4:15 - four fifteen = (a) quarter past 4
4:20 - four twenty = 20 past 4
4:25 - four twenty-five = 25 past 4
4:30 - four thirty = half past 4
4:35 - four thirty-five = 25 to 5
4:40 - four forty = 20 to 5
4:45 - four forty-five = (a) quarter to 5
4:50 - four fifty = 10 to 5
4:55 - four fifty-five = 5 to 5
5:00 - 5 o'clcok = 5 o'clock