I don't see why they (AMEX Redbird) would care whether these amounts are round numbers or not. What do you want to hide from them? They see the transaction and know that you load the card with a credit card as payment, whether the amount is round or not.
The only reason to use odd numbers would be to hide the fact that you are loading a re-loadable card from your credit card issuer, so they think it is legitimate spend and not loading a card. So I think it will make no difference whatsoever. Just my 2 cents.