I was a server a long time ago as my family owned restaurants and I never cared if someone made the total with tip a round number. People who pay with cash almost always total up to a round number so the credit card portion doesn't impact it at all. Even if everyone paid by card, no one would care that someone tipped $6.59 instead of $6 or $7. Not sure what the issue could even be.
Now I often make the grand total a round number especially when I travel on business. My company has a really silly requirement that the meal reimbursement for each day cannot exceed $50 not even by a penny and not even if you go under on other days, it's a hard limit. After having to reimburse the company for $3.10 when I first started, I now round up to make it easier to remember what I have remaining for a day. If I spend $12 on lunch I know I have $38 left for dinner.