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	$114.69	11.550%	$127.9367	$127.94	$127.95	$127.90
Purchase #2	$135.89	11.171%	$151.0703	$151.07	$151.05	$151.10
Purchase #3	$207.35	7.307%	$222.5011	$222.50	$222.50	$222.50
Purchase #4	$7.56	7.563%	$8.1318	$8.13	$8.15	$8.10
Purchase #5	$54.82	13.770%	$62.3687	$62.37	$62.35	$62.40
Purchase #6	$131.70	8.789%	$143.2751	$143.28	$143.30	$143.30
Purchase #7	$9.82	4.690%	$10.2806	$10.28	$10.30	$10.30
7 purchase totals =	$661.83		$725.5643	$725.57	$725.60	$725.60