You don't need to store 25:20 in the database though - your app can use a window that treats a day as "from 5 am today until 5 am tomorrow" and adds 24:00 to the times for tomorrow.
In Dublin (I was there 2001 to 2004), Time tables show buses just after midnight, such as 1:20am as running at the time 2520 - so there are visible close to the end of the day. If you are looking for buses around midnight this is very user friendly - better than looking at the other end of the time table for 0120.
I think logically that 24:00:00 is exactly one day later than 00:00:00 - but I see from following the URL, that there are other complications...
