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	$158.92	11.617%	$177.3817	$177.38	$177.40	$177.40
Purchase #2	$144.60	11.653%	$161.4502	$161.45	$161.45	$161.50
Purchase #3	$101.41	8.756%	$110.2895	$110.29	$110.30	$110.30
Purchase #4	$50.65	11.427%	$56.4378	$56.44	$56.45	$56.40
Purchase #5	$238.69	7.188%	$255.847	$255.85	$255.85	$255.80
Purchase #6	$113.26	12.752%	$127.7029	$127.70	$127.70	$127.70
Purchase #7	$118.53	7.132%	$126.9836	$126.98	$127.00	$127.00
7 purchase totals =	$926.06		$1,016.0927	$1,016.09	$1,016.15	$1,016.10