Just copy the ROUNDUP formula down the column. Select the cell, select the
bottom right-hand corner and it will turn into a square "fill handle" which
you can drag down. If your formula is in a cell adjacent to the column with
the data, if you double-click the fill handle it will fill down the column
as far as the data stretches.
This is another option,
probably similar to Ron's
loops through column G and changes rounds up the value
Sub RoundUpCells()
Dim TheRange As Range
Dim TheCell As Range
Set TheRange = Range("G1", Range("G65536").End(xlUp))
For Each TheCell In TheRange
TheCell = Application.RoundUp(TheCell, 2)
Next TheCell
End Sub