Program to calculate tax:

float tax (float) ;

int main()

{

                float purchase, tax_amt, total;

                cout << "\nAmount of purchase: ";

                cin >> purchase;

                tax_amt = tax(purchase);

                total = purchase + tax_amt;

                cout.precision(2);

                cout << "\nPurchase is: " << purchase;

                cout << "\nTax: " << tax_amt;

                cout << "\nTotal: " << total;

                return 0;

}

float tax (float amount)

    {

        float rate = 0.065;

                return(amount * rate);

    }