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	$216.91	5.817%	$229.5277	$229.53	$229.55	$229.50
Purchase #2	$244.53	5.311%	$257.517	$257.52	$257.50	$257.50
Purchase #3	$205.98	4.730%	$215.7229	$215.72	$215.70	$215.70
Purchase #4	$42.65	11.358%	$47.4942	$47.49	$47.50	$47.50
Purchase #5	$27.77	3.323%	$28.6928	$28.69	$28.70	$28.70
Purchase #6	$167.29	13.777%	$190.3375	$190.34	$190.35	$190.30
Purchase #7	$41.42	3.104%	$42.7057	$42.71	$42.70	$42.70
7 purchase totals =	$946.55		$1,011.9978	$1,012.00	$1,012.00	$1,011.90