here's a full sample on adding to the Format method of a DatagridTextBoxColumn...
Dim dgStyle As New DataGridTableStyle()
With dgStyle
.AlternatingBackColor = Color.LightGray
.BackColor = Color.WhiteSmoke
.ForeColor = Color.MidnightBlue
.GridLineColor = Color.Honeydew
.GridLineStyle = System.Windows.Forms.DataGridLineStyle.Solid
.HeaderBackColor = Color.MidnightBlue
.HeaderFont = New Font("Arial", 8.0!, FontStyle.Bold)
.HeaderForeColor = Color.White
.LinkColor = Color.Teal
.MappingName = "Appointments"
.SelectionBackColor = Color.Yellow
.SelectionForeColor = Color.DarkMagenta
End With
Dim grd5 As New DataGridTextBoxColumn()
With grd5
.HeaderText = "Description"
.MappingName = "Description"
.Width = 75
End With
Dim grd6 As New DataGridTextBoxColumn()
With grd6
.HeaderText = "Dur"
.MappingName = "Duration"
.Alignment = HorizontalAlignment.Center
.Width = 30
.Format = "c" ' <<< This will set the column to currency
End With
dgStyle.GridColumnStyles.AddRange(New DataGridColumnStyle() {grd5, grd6})
DataGrid1.TableStyles.Add(dgStyle)