I'm building a gambling website. All financial transactions from and to external sources (credit cards, money transfer systems) are subject to commission. Amount of the commission depends on the source selected. And moreover, it changes periodically. These external commissions go to the payment systems.
Also some inner transactions are subject to commission. Inner commissions depend on the type of the game user playing. These internal commissions go to gambling website, it is the income.
I'm looking for the best way to store the history of transactions and commissions. Should they be stored in one table TRANSACTIONS (with a connection between payment and commission) or should I have separate table COMMISSIONS.
The purpose of storing is to represent the history of transactions to the user and of course for internal bookkeeping (in order to always know how much have we paid to payment systems and how much have we earned ourselves).
Any advice greatly appreciated.