You can't get much hashing power from just a few pennies on Nicehash considering the cost of renting hashrate from them, and as TryNinja said, many small transactions creates more inputs that results in higher fees when the coins are moved, so this makes sense for Nicehash to do. The fee for 0.001BTC to 0.05BTC seems just a bit high to me at 0.001BTC, but there's none at or above .05BTC, which is what I expect most people are depositing at one time or more. Can't blame a service for trying to lower their operating costs for unreasonable transactions.
When we try to look at between 0.001BTC - 0.05BTC then such fee is really high. Therefore, people would really just pushed to make bulk amount transactions rather than doing on a dust amount so i cant blame them if they do set out such rule because even if im the owner i would definitely do such thing to get rid of those unreasonable tx.
