Yes, I got this same error. I agree it is a rounding error (at least in my instance). Box 3 is rounding up while Box 4 is rounding down. So for test purposes only, I rounded up Box 4 and error message no longer appears. As mentioned before, rounding the numbers are just for test purposes, so you can validate why the error message is happening. You need to set Box 3 and Box 4 back to the original correct values, you will get the W2c error message, but you can just ignore it and move forward.
