Staring at the Income/Frequency histogram, I am wondering why there is more clusering around the 10s and not the 5s. Ex: more salaries clustered around 60K, 70K

Staring at the Income/Frequency histogram, I am wondering why there is more clusering around the 10s and not the 5s. Ex: more salaries clustered around 60K, 70K, and 80K than around 65K, 75K, and 85K. I wonder if there is a tendency (intended or otherwise) for employers/managers/etc to push salaries towards these numbers. Do they seem more 'round'? I have some experience here, but I don't know if its really a trend. I was bumped up a while back from an 'uneven' salary to one of those clustering points. It was a small, strange, increase amount, but it was a welcome increase nonetheless!