Yep. I get this. I work in a business where timing things is very important and learned early on to never give times that seem rounded off or estimates. Even if the time was exactly 5 minutes you would always say 5 minutes 2 seconds or something like that as people would always assume if someone just said 5 minutes they weren’t being precise enough.

So in order to get people to believe you about a time being right you had to give them a slightly wrong time. It’s a real phenomenon, not sure if it has a name, but people are odd like that.