How to Roundoff Timespan to 30 mins

Question

if TimeIN late by 5 mins or <= 34 mins considered 30 mins late

and if 35 above example 09:35 then it must be 10:00

 

and in between break if less than 30 mins it considered as 30 min break and so on,

and if time out is less than 30 mins round down:
example:

4:08 = 4:00

4:29 = 4:00

03:59 = 03:30