When you mouse over your chart you may see long decimal places after the value. If you want to remove the decimal places from your column values, you'll need to cast your values as integers.
In the Data Pipeline of your chart, click +Add Step and choose Add Column from the dropdown menu. Name your column, and enter the following into the formula field:
CAST("A" AS INT)
Where "A" is the name of your original column.
If you need to hide your original column, add a Hide Columns step in the Data Pipeline.