Here is one way to perform the computations 'at once'. The following macro will round to the nearest whole number. It assumes the column is column A. If your column is not A, change the three "A" references to your column letter, i.e. "F", "M", etc.
Copy the following macro to the clipboard:
Sub Percentage_and_Round()
Dim i, LastRow
LastRow = Range("A" & Rows.Count).End(xlUp).Row
For i = 1 To LastRow
Cells(i, "A").Value = Application. Round(Cells(i, "A").Value * 1.05, 0)
Next
End Sub
Press ALT + F11
In the menus at the top of the VBE, select INSERT > MODULE
Paste the macro into the editing area to the right.
Close the VBE and return to the worksheet.
Press ALT + F8
When the Macros window opens, highlight the macro and click 'Options..'
Enter a letter to be used as a keyboard shortcut and click 'OK'.
Close the Macros window.
To run the macro, press Ctrl + your shortcut letter.