Is it possible to format cells to automatically round a number, for example:

1.37 to 1.25 or 1.38 to 1.50

I have used the mround formula when work with two different cell, i.e.,
in cell b2 I use this formula: =mround(a2,.25) and it works.

However, I would like use the format page (cntl+1) to do it automatically in
the cell I am working. Any help would be great. Thanks.
Johnnie