I found an exam online from the MIT that states:
You have two hours (academic time, 110 minutes) to complete the exam.
What is this academic time unit and where does it come from?
The 10 minute interval given here seems to be common in the US, while in Europe 15 minutes is also in widespread use, but some universities also use 5 minutes.
It is to solve a rather practical scheduling problem: If one lecture ends on the hour sharp, and the next begins on the hour, you would have only zero time to walk an often non-zero distance to get to your next lesson/lecture/exam/whatever, requiring asymptotically infinite velocity to cover that distance - a theoretical and practical impossibility.
In order to solve this, European universities invented the so called "academic quarter", which is in use at some universities until today. It means that events start 15 minutes after their scheduled time.
The abbreviations c.t. (for cum tempore, en. "with time"), which means 15 minutes after the scheduled time and s.t. (sine tempore, en. "without time") which means exactly at the scheduled time stem from this. In some European universities (especially german), times are assumed to be c.t. unless stated otherwise.
Berkeley calls this 10-minute interval "Berkeley time", and MIT seems to prefer "academic time", although I have never seen it been used with intervals, only with instants in time so far.
There are many variations of this scheme, and many universities have their custom practices. Some start at the hour sharp and end five/ten/fifteen minutes early, some start five/ten/fifteen minutes after the hour and end sharp, and at some universites lectures both start five/ten/fifteen minutes late and end five/ten/fifteen minutes early, and maybe some universities use even other schemes (a comment refers to seven past the hour).
At my university, the academic quarter is used both at the start and end, since our campus is rather large and for some locations, you actually need almost 30 minutes when walking, and 20 when talking public transport in between those locations.
From personal experience, universities tend to move away from using c.t. times, and rather list actual (s.t.) start times on official resources/documents (e.g. 10:15 as start for a lecture), while students and professors would still refer to those lectures by their time slot (in this case 10 o'clock lecture) and make use of whatever length their university uses as "academic quarter" in colloquial speech.
(Addition from comments):
At some universities, the academic quarter is also used as the time students have to wait for the lecturer. If the lecturer is late, but does not arrive within the academic quarter without any more information, students may assume the lecture is cancelled and can leave without the fear of missing any material.
(I recommend not leaving without being sure this is policy at your own university as well)
It is a scheduling problem. If you schedule two lectures directly after one another, then you need to add some time for the students to walk from one lecture hall to the next. So an "academic hour" is less than an actual hour, to allow for that.
At many colleges, "1-hour" classes are 50 minutes long to provide 10 minutes of break time between classes. For example, a 2-hour class starting at 10:30am would end at 12:20pm, which is 110 minutes long.