shipping costs b-post

If that is part of the package you are selling, it must be included in the daily receipts. It is part of your "income".

It does not matter if you then have to pay that amount 1-to-1 to b-post. If a customer pays you that amount, it is income for you.That's right, you sell something and the full price your customer pays for it must be considered income. As NZ says, it doesn't matter if part of it is simply passed on.