I'm taking an online statistics course, and need help with a certain concept involving percentiles.

Heres the question:

The following are test marks:

38 54 65 57 66 42 62 65 71 67

43 60 84 58 72 67 80 88 70 93

55 60 68 74 98 59 76 71 45 56

If Jermone scored a 76%, what was his percentile?

Here is the example answer that the textbook gave:

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Great work! Your solution may have looked like this:

P=100((24)+0.5(1)/30)

P=81.6667

Because it is a percentile, we round down to 81%

My question is:

Why is it that we would round the percentile down. According to the rounding rule, a percentile of 81.66667 should be rounded up to 82%, not rounded down to 81%. If anybody has any insight it would be greatly appreciated.