There is no 100% right way to make a box. Generally speaking, a +-10% variation in box size is inaudible. Also, any given driver will perform well in more than one size or style of box. Another thing to consider is that 100% dead on correct is highly subjective. 100% dead on correct for what? Rap, rock, burp box, in an SUV, pickup, trunk car? 200 watts or 2000 watts? All of that makes a difference.
As programs go, I like WinISD (beta). Of course, when you plug TS numbers into it for a given driver and then select, say, ported... it will usually come back with some outrageous recommendation like 12 cubic feet for a 12 but, it does that because it initially optimizes for the driver. In car audio, we can rarely, if ever, afford to design with driver optimization in mind, so we have to compromise and play with different sizes & tuning frequencies until we find an arrangement that meets our wants and needs.
If you don't know how to read a response curve, do some research on that so you'll have a better understanding of what 100% dead on is for you. Because it will be different for me or the next guy.... because again, that's a loaded term.