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	$135.91	11.174%	$151.0966	$151.10	$151.10	$151.10
Purchase #2	$62.29	4.657%	$65.1908	$65.19	$65.20	$65.20
Purchase #3	$40.49	12.790%	$45.6687	$45.67	$45.65	$45.70
Purchase #4	$188.37	12.772%	$212.4286	$212.43	$212.45	$212.40
Purchase #5	$195.85	12.261%	$219.8632	$219.86	$219.85	$219.90
Purchase #6	$191.51	7.683%	$206.2237	$206.22	$206.20	$206.20
Purchase #7	$98.45	13.401%	$111.6433	$111.64	$111.65	$111.60
7 purchase totals =	$912.87		$1,012.1149	$1,012.11	$1,012.10	$1,012.10