Final answer:
To find the total cost including sales tax, multiply the price of the item by the sales tax rate. Then, add the sales tax to the price of the item.
Step-by-step explanation:
To find the total cost including sales tax, you need to first calculate the amount of sales tax by multiplying the price of the item by the sales tax rate expressed as a decimal. In this case, the sales tax rate is 9.5% or 0.095. So, the sales tax on a $9.78 item would be $9.78 * 0.095 = $0.93 (rounded to the nearest cent).
To find the total cost, you would add the sales tax to the price of the item. Therefore, the total cost, including sales tax, for an item with a price tag of $9.78 would be $9.78 + $0.93 = $10.71.