yep, it is definitely just a guidance, I don't think the numbers can be precise actually and with rounding that pushes them even farther off.
have you set your goals? It gets easier because you do tend to eat the same things over and over so you can just go to your "recents" list. I would take the effort to make sure that you have the brand of whatever you are eating when you track. Also, I tend to eat the same breakfast and lunch most days. So I have those under my meals and add them from there.