Final answer:
In mathematics, to calculate the total cost including a 6.75% sales tax on items costing a combined $20.98, first determine the sales tax by multiplying the total cost by 0.0675. After rounding, the sales tax is $1.42, making the final price including sales tax $22.40.
Step-by-step explanation:
The subject of this question is mathematics, specifically dealing with the calculation of sales tax and total cost, which is suitable for a middle school level. To find the total price of the items before tax, you add the individual costs together. Since $8.99 + $11.99 equals $20.98, this is the total before tax. To calculate the sales tax, convert the percentage to a decimal by dividing by 100 (6.75% becomes 0.0675) and multiply this by the total cost of the items. Finally, to find the total price including tax, add the original total to the sales tax.
To provide a specific example, for a total price of $20.98, multiply by 0.0675 to find the sales tax amount, which would be approximately $1.41615. This value is then rounded to the nearest hundredth, resulting in $1.42 as the sales tax. Adding this to the original total, the final price including sales tax is $20.98 + $1.42, which equals $22.40.