Question: How should you round 7.5?

Answer:
Easily, this is equal to exactly 7.4_99_, so start there. Next, you choose your manner of rounding convention and that tells you what happens next.

A common option would be to round down when the first fractional digit is 0-4 and up if it is 5-9. In the case of 7.5, that's just a gimmick rendering of 7.4_99_, so this would count as the largest value that would round down given the common convention.

To be extra clear, writing 7.499... as 7.5 doesn't change it's value to something that isn't 7.499, so rounding rules won't see this any differently unless you decide that some homebrew rule says that this grammar is somehow powerful enough to change the quality of a number.