Generally speaking, there should be no issue with rounding up to a whole number, although I would question the reason to do so, especially when rounding to 2 decimal places would provide a more accurate figure, since it would be closer to the original number that you calculated. For example, consider a random number: 2.64987. As a ratio, rounding this number to 2 decimal places would result in a ratio of 2.65:1. On the other hand, rounding to a whole number would result in a ratio of 3:1. Notice that 2.65:1 is more accurate than 3:1, since rounding to 2 decimal places adds a much lower value to the original number than rounding to a whole number.
As such, unless otherwise stated, I would recommend rounding ratio figures to 2 decimal places.
I hope this helps!
