Exactly what value is present? Is the value exactly 0.15, or is it something like 0.14999999? You are correct that 0.15000000 should round up to 0.2, but 0.149999999 will round down to 0.1 (and both 0.150000000 and 0.14999999 may display as 0.15). Look more closely at the value (extend decimal places, maybe) and determine exactly what value is stored in the cell.