I thought they odds were the rounded percentage, but it appears that 6.4 for example which would be 1562.5 so rounded to 1563 is invalid.

So are you in fact rounding down for 0.5?

Yes, 0.5 would rounded down. You can double-check the full odds table here:

Thanks. I think there are only 4 incorrect ones

Hello Michael, which 4 are these? are they all .5 values?