Our roads take a beating from big trucks. Those big trucks carry everything we consume. Therefore, a sales tax is indirectly related to the conditions of roads. It ought to be the case that a significant portion of our sales tax goes towards repairing roadways as well as investigating new ways of innovating roads (new materials, environmentally friendly, EV chargers built into roads, new designs, faster repairs, etc).
To ensure this, we would need to be able to audit the taxes collected by the government.
The basic idea here is that a tax on commerce ought to go toward improving the infrastructure of said commerce. On a broader note, any tax ought to support the infrastructure of its taxed subject. The integrity of this idea must be preserved, and so it should be subject to independent audits specifically to prevent money laundering activities.