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	$203.82	5.404%	$214.8344	$214.83	$214.85	$214.80
Purchase #2	$53.49	4.834%	$56.0757	$56.08	$56.10	$56.10
Purchase #3	$208.55	4.469%	$217.8701	$217.87	$217.85	$217.90
Purchase #4	$245.68	9.843%	$269.8623	$269.86	$269.85	$269.90
Purchase #5	$57.78	12.745%	$65.1441	$65.14	$65.15	$65.10
Purchase #6	$248.72	4.334%	$259.4995	$259.50	$259.50	$259.50
Purchase #7	$59.47	4.864%	$62.3626	$62.36	$62.35	$62.40
7 purchase totals =	$1,077.51		$1,145.6487	$1,145.64	$1,145.65	$1,145.70