If the sales tax rate is 9.5%, what would be the total cost of an item priced at $9.78 including sales tax?

To determine the total cost of an item including sales tax, you need to calculate the amount of sales tax and then add it to the original price of the item.

First, convert the sales tax percentage into decimal form by dividing by 100:
9.5% = 0.095.

Next, calculate the sales tax on the item priced at $9.78:
Sales Tax = Price × Sales Tax Rate
Sales Tax = $9.78 × 0.095 = $0.9281.

Now, add the sales tax to the original price to find the total cost:
Total Cost = Original Price + Sales Tax
Total Cost = $9.78 + $0.9281 = $10.7081, which rounds to $10.71 when considering currency.

Thus, the total cost of the item, when including sales tax at 9.5%, is $10.71. This aligns with the answer choice given as option A, confirming it as the correct response.