Dashboard won't add decimal numbers

Dashboard won't add decimal numbers

I'm not sure this is really a bug, but there no longer seems to be a help forum and I can't find the answer.
We use a decimal system in order to keep track of our inventory. I am trying to set up the dashboards in order to keep track of what has been sold, but the dashboards only add the whole numbers, not the decimals, so if we have sold 3.0, 0.5 and 0.1, the dashboard total is only 3. Is there any way to get around this?