Hi James,
Sorry for the delay in responding.
To make the GridGroupingControl display a decimal like 345.5462 as 345.55, please use the code given below.
this.gridGroupingControl1.TableDescriptor.Columns["Col0"].Appearance.AnyCell.CellValueType = typeof(decimal);
this.gridGroupingControl1.TableDescriptor.Columns["Col0"].Appearance.AnyCell.Format = "c";
Please refer to the attached sample that illustrates the same.
http://websamples.syncfusion.com/samples/Grid.Windows/F67366/main.htmKindly let me know if this helps you.
Best regards,
Golda