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	$185.40	4.773%	$194.2491	$194.25	$194.25	$194.20
Purchase #2	$38.31	3.102%	$39.4984	$39.50	$39.50	$39.50
Purchase #3	$102.74	5.179%	$108.0609	$108.06	$108.05	$108.10
Purchase #4	$228.71	11.531%	$255.0826	$255.08	$255.10	$255.10
Purchase #5	$212.84	4.251%	$221.8878	$221.89	$221.90	$221.90
Purchase #6	$90.43	10.113%	$99.5752	$99.58	$99.60	$99.60
Purchase #7	$49.48	5.156%	$52.0312	$52.03	$52.05	$52.00
7 purchase totals =	$907.91		$970.3852	$970.39	$970.45	$970.40