Final answer:
To calculate the total cost of Robert's purchase after tax, multiply the cost of items by the sales tax rate to get the sales tax amount, then add it to the original cost. The total cost including a 7.25% tax on a $30.45 purchase is $32.66.
Step-by-step explanation:
To calculate the total cost of Robert's purchase including tax, first we need to determine the amount of sales tax. We can do this by multiplying the cost of the items before tax by the sales tax rate, then add the resulting sales tax to the original amount.
First, we convert the sales tax rate from a percentage to a decimal. For a sales tax rate of 7.25%, the decimal form is 0.0725. Then we calculate the sales tax: $30.45 × 0.0725, which equals $2.207625. We can round this to the nearest cent, giving us $2.21 in sales tax.
Finally, we add the sales tax to the original cost to get the total cost: $30.45 + $2.21, which equals $32.66.
The total cost of Robert's purchase including sales tax is $32.66.