Certain stocks have a min tick increment size of .05 rather than .01. So for example if I try to create a stop order at $12.03 for a .05 tick it will reject my order. How do I check for the minimum tick increment of a particular security? If I can't, then how do I identify that a stop order was just rejected because I didn't conform to the min tick increment?

I am trying out the code below but am not sure whether the status would be cancelled or invalid whenever the tick size issue happens. 

if (fill.Status.ToString() == "Canceled" || fill.Status.ToString() == "Invalid" && Securities[fill.Symbol].Invested)
stopTickets.First(x => x.Symbol == fill.Symbol).Update(new UpdateOrderFields { StopPrice = Math.Round(calcStop(dir, fill.FillPrice) * 20) / 20 });