I have a pen question. It is really a dosing question but I am getting all messed up and doubting my calculations. I have a pep that we are researching at 0.5 in a 1 ml syringe. When I put that dosage in the pen cart it comes to 25. The clicks on the pen don't have halves so will I have to pick either 20 units or 30 units or am I over thinking this>