The difference actually didn't tally, customer asked me about this in the morning and I don't know what to answer. Now in the evening, it APPEARS THAT the reason is due to this round-off of 1 decimal point. (0.04% rounded to 0%; while 0.06% rounded to 0.1%)
But then of course, I am hoping anyone here is experienced enough to give me a concrete answer/confirmation. Thanks.