I remember doing a mobile home park appraisal and the guy gave me the old appraisal done on the property. It was something like $1,012,681 (don't recall the exact figure but remember it was "rounded" to the nearest dollar). Something was clearly off about that number and I've never heard of the guy doing the appraisal, despite the property only being about an hour from the office.
Farmland is one property type where it might not look so strange to have a figure like the above, as the market typically rounds to the nearest price per acre, rather than a rounded overall price, in most cases.
In general, my thoughts on rounding are that in many cases, I will not round as much on the individual approaches, but often have a more rounded figure on the final value opinion. I scanned through the first and last pages of this thread and haven't read the rest, but if the market seems to round to the nearest $50,000 or $100,000, yet I have a sales comparison approach value of $1,365,000, that says nothing about whether I am so precise at valuations, but rather, recognizing that if everything is rounded in one direction and the variance in that market errs to the same direction, one could effectively "miss the boat". Or, maybe the central tendency of the adjusted unit prices are $38.61 to $39.63 per square foot, but I round to $40 per square foot, then subsequently round up from there to the nearest $50,000-$100,000, which would result in a value being +/- 5% above the central tendency. Ideally, in the aforementioned example, the other approaches would be such that the final value would neatly fall into the nearest $50,000 or $100,000 increments. Leasedfee's quote of rounding as the market rounds is spot on, but I'd rather be off by not rounding as much as the market rounds than by rounding in the direction opposite that the market ends up rounding.