van sale

1- we will setup for a commercial company.

2- a goods added to van.

3- a sales representative distribute from van to small customer.

4- every small customer will take an invoice without tax but the price include tax.

4- in the next day the sales representative  group the small invoices to on invoice and distribute the price of item to amount without tax and tax amount.

5- added the money to Treasury.

how i make this cycle ?