Did you previously set those cells to "Comma Style"?
If you look next to the icon for "Currency Style", you've got "Percentage", "Comma" and "Add/Remove Decimal Place".

Once you've set a cell to Currency or Comma Style, even removing the decimal places leaves that style set, and sets an invisible 'decimal tab' point.

Try going to Format -- Cells -- Number
Then, select Category as 'Number' and set the required number of decimal places. This may fix it.

Regards,
BizMark