Accounting concept

Dear Colleagues,

There is a Cargo Handling Company. It maintains its books of accounts in Tally ERP9. Here, all the revenue due from parties is passed through sales vouchers. The expenses such as electricity, stationery, etc is shown in journal vouchers. Earlier such entries were passed through purchase vouchers.

Plz guide me as to what is the correct accounting mathod that must eb adopted by the company.

Tahnks in advance.