I have a list of a few thousand times in this 24 hour format:

14:54:12
04:50:46

I need to convert all to 12 hour format rounded to the nearest minute,
example:

14:54:12 would be 2:54 PM
04:50:46 would be 4:51 AM

I am totally lost and dread having to convert thousands by hand, but that's
the exact format the job requires. Any help is greatly appreciated.