Final answer:
A sales tax is a regressive type of tax, as it places a higher relative burden on lower-income individuals than on those with higher incomes.
Step-by-step explanation:
A sales tax is an example of a tax that uses a regressive tax rate structure when compared to its tax base. Under a regressive tax system, individuals with higher incomes pay a smaller percentage of their income in taxes, meaning the tax burden falls more heavily on those with lower incomes. For instance, a sales tax affects lower-income individuals more because they spend a larger portion of their earnings on taxed goods, while the wealthier can save or invest a greater share of their income, which is not subject to this tax.