There is no way to round the forecast numbers from demand planning. You can set the main Demand Planning client to have 0 decimals in the Forecast Table, but when adjusting the forecast from aggregated levels the resulting forecast will be with decimal points, so will the forecast be when it’s calculated.
The reason for this is that it is not smart to round the forecast, is that the forecast is used for further calculations in MS/MRP/IPR and its never vice to round the number in the middle of an calculation (it introduces rounding errors), you should round at the end for the calculation.
Example: Say the forecast in 0.5 per period, in MS you choose to add together 4 periods as the lot/batch size. This will give you a lot size of 2 units, but if you round the forecast before MS the lot size will become 4 which is a huge difference.
I am not an expert in all details in MS but I think that you can setup decimal rules in there so that you don’t show any decimals.