Riders are more accepting of surges that are NOT round numbers, because consumers feel more thoughts went into the calculation of the surge pricing. This was shared on an interview at NPR, where Uber's economist shared a factor in when people are accepting of surge pricing.
From an Uber rider's perspective, Keith says, a round number surge like two times looks like the company is just slapping on a higher price tag because it's raining. But when it's 2.1 times as much, we think there must be a complex algorithm (which there is) coming up with that figure. The ride, then, is surely worth 2.1 times as much. (source)
Similar research with eBay:
Economists found sellers who priced their goods with round numbers (i.e. $50 instead of $49) sold their items quicker. The researchers hypothesize that round numbers signal the sellers' impatience to sell and, thus, their willingness to accept a lower price. In other words, round numbers signal carelessness or imprecision.