[rahimnathwani]

"if I were to round a 21.4% to 20%"

Right, but you'd round 21.4% to 21%, not to 20%.

[infogulch]

You're assuming that you can only round to the nearest 1% which is not true at all. If you round to the nearest confidence interval and the CI is 5% then you would round to 20%. That said, I would prefer both the precise number and CI communicated together like sibling comment mentions.

[pushrax]

Or ideally keep 21.4% and include the 95% CI. There’s nothing misleading about the extra precision when the CI is included.

[yowlingcat]

Agreed. Actually, I wish the norm was to communicate percentages with confidence intervals by default, because I feel like the tacit implication is colloquially "100% CI unless communicated otherwise."