So here is the answer. Given that the item originally costs $6.45 and marked it up to 20%, the new price would be $7.74, because 20% of 6.45 is 1.29. Now that it is 5% off, the new price would be $7.353. Now that it has an additional sales tax of 6%, the total amount would be $7.79 or $7.80. Hope this answers your question. Have a great day!