The formula bar will display the actual value/formula, while the cell will display the text that is printed. A time of 5:15 is the same as 5:15 AM which is the same as 0.21875
Another example is the time 27:45. This is the same as 1/1/1900 3:45 AM, which is the same as 1.15625
The true value stays the same, the only difference is how XL interprets it. A question I would have is, "why does it matter?"
But, possible ideas:
1. Hide the formula bar
2. input the time as '5:15 The single apostrophe will cause XL to take what you type literally, and not convert it. Downside is that it is now a text string rather than a number.