I figured out the solution to my problem. I was using the afterupdate event. I should use the BeforeUpdate event to validate the event and set cancel to True as shown in the code example below.

Private Sub Basis_BeforeUpdate(ByVal Cancel As MSForms.ReturnBoolean)
'Validates the input is numeric
If IsNumeric(Me.Basis.Value) = True Then
Me.Basis.Value = Format(Me.Basis.Value, "$ ##,###,##0.00")
    Else
    MsgBox ("Invalid Value, Please Re-enter")
    'Value Reset to Blank
    Me.Basis.Value = ""
    'Returns to field for input
    Cancel = True
    End If

End Sub

My thanks to those who responded with suggestions.