At what increments do you increase your volume at?

My friend and I are having an argument.
So everyone knows it's either an even number or a 5. So for example 20, 22, 24, 25, 26, 28 and 30. But personally I would get rid of 28 and replace it with 27.
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Like when watching Netflix say the volume is too low and it's sitting on 25 but 30 is too high, would you put it to 27?
At what increments do you increase your volume at?
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