500
Imagine you buy a house and the price of the house is 215,589 Euros.
One day you are talking to some friends and you tell them about the house. You say: "The house cost me 200,000 Euros more or less"
Another day you are talking to your parents and you tell them about the house. You say: "The house cost me 220,000 Euros more or less"
Which is the best rounding for the price of the house?
The best rounding is the second one, the price that you tell to your parents. This is because it aproximates better the real price of the house.