Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$197.58	8.436%	$214.2478	$214.25	$214.25	$214.20
Purchase #2	$206.50	9.153%	$225.4009	$225.40	$225.40	$225.40
Purchase #3	$112.61	9.468%	$123.2719	$123.27	$123.25	$123.30
Purchase #4	$205.75	13.284%	$233.0818	$233.08	$233.10	$233.10
Purchase #5	$110.96	8.669%	$120.5791	$120.58	$120.60	$120.60
Purchase #6	$103.96	7.602%	$111.863	$111.86	$111.85	$111.90
Purchase #7	$43.92	3.652%	$45.524	$45.52	$45.50	$45.50
7 purchase totals =	$981.28		$1,073.9685	$1,073.96	$1,073.95	$1,074.00