I have a call option in my portfolio that varies in price between 0 and .05. When I try to set the price to 0, it will not let me do it. If the previous price was .05, it just stays at .05. The best I can do is set the price at .00001. That works and almost gives me the correct market value (0)but I'm curious as to why I can't set it to 0 exactly?