Round time worked to the nearest 15 min

Round to the nearest 15 min using a 7 min grace period if you login at 707am you would round to 7am but if you logged in after 708am you would round to 715am. This would be very useful for our payroll because this is how we pay and we use another program that we have 16 guys on that has this feature and we really like it and would appreciate if you could figure out how to make it work on your system thank you