Technically you can have noticeable differences before you even make it to 1 cent. For example, if you're trying to determine if a result of a calculation is negative, 0, or positive for whatever reason. With floats/doubles, you would probably need to consider "0" to actually be "a number sufficiently close to 0, if not 0 exactly" and then remember to handle that everywhere.
It can also be noticeable if you're just trying to calculate something like "is the invoice paid off". Maybe your view layer is showing $0.00 balance to the end user, but the backend hasn't correctly rounded off those extra bits from a floating point calculation, so your backend logic is now saying the invoice is not actually fully paid off, even if the end user has no idea what they could possibly still owe.
It can also be noticeable if you're just trying to calculate something like "is the invoice paid off". Maybe your view layer is showing $0.00 balance to the end user, but the backend hasn't correctly rounded off those extra bits from a floating point calculation, so your backend logic is now saying the invoice is not actually fully paid off, even if the end user has no idea what they could possibly still owe.