Rounding Time and Cut and Paste issues

I have this long list of times and I need to round each in this manner;
0-29 seconds stay the same
30-59 seconds round up a minute
So if the time is 14:05:29 it should read 14:05
And it the time is 22:13:30 it should read 22:14.
Is there a function for this?

Also like below, If I create a new column to the right using a function to round off these times, it's dependent on the column(original list of times) to the left isn't it?
23:44:12 23:44
18:22:45 18:22
02:03:34 02:04
13:45:46 13:46
I suppose if I wanted to, I can't just delete the column to the left without messing with the figures in right hand column. I'm wondering if there is a way I can round these figures in a similiar manner to changing the format of the cells so that I don't have to create another column altogether. Or instead, is there a way that I could cut and past the rounded off times(just the numbers) from the right column to anywhere else in the document without carrying the function quality?
Thank you Kindly,
Anna