That’s it. That’s the tip. WCAG doesn’t round.
In any of the success criteria where digits are used, they do not round those measurements. You may be trying to hit the minimum target area of 24 by 24 pixels. However, if you churn out 24 x 23.9 pixels (bear with me) you have failed the criteria.
Let’s look at the example you’ll likely run into this with: color contrast. Calculating contrast we use a foreground and a background. Using the WCAG 2.x algorithm, we have a contrast ratio of 4.498799879:1. This is a fail for body text as it is less than 4.5:1.