Rounding and truncation are similar, but with rounding being a broader function over truncation in this use. The idea behind rounding in the case of the Yiggy was that either method would increase quant noise, rounding would result a potentially less quant error and they decided it was low enough in level not to address it in by using a dithering filter. Adding dither would have added cost and complexity to the design and did so knowingly it would not measure in an ideal manner. In the test, it had shown that the rounded method used produced the exact result as truncating. No surprise in that part as rounding can produce the exact same figure. Rounding will in some cases, produce a slightly different result over truncation and have an very minor difference in quant error in comparison to truncation.
In large, this won't present much of an issue to most of recorded music. To the ones that it may have, will be quite low in level.
