Question

Your state charges 5% sales tax on nonfood items. You're buying a light bulb for $3.00, cereal for

Answer 1

We first add the tax to the non-food items.  We have ($3.00+$.50)*1.05=($3.50)*1.05=$3.675 (Which can be rounded up to $3.68, since we can't have a fraction of a cent).

Now, we add the cost of the food to $3.68.  As a result, we have $3.68+$2.50=$6.18 as the total bill.