That would be fine as that is what it has cost you (you can also take the foreign currency transaction fees on your credit card statement as a tax deduction too).
It is best, however, to try and split out your personal transactions from your business ones - so set up a new bank account and credit card for business expenses and income only for example. This makes things much easier if the IRD decide to investigate you or ask you questions as that way you only have to look through the business account and can show that there are no personal transactions in there other than transferring the profit to your personal account for you to spend!