Calculate the "Total With Tax" for the first transaction.

Copy and paste the formula down the column to calculate the total with tax for the other transactions.

In cell Q$12,$ calculate the "Total Revenue Before Tax".

In cell Q$13,$ calculate the "Total Tax Collected."

Use the "Tax Rate" in cell Q$8$ and the "Total Revenue Before Tax" you calculated in Q$12$ to calculate the total tax collected.