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	$179.59	9.631%	$196.8863	$196.89	$196.90	$196.90
Purchase #2	$6.74	5.413%	$7.1048	$7.10	$7.10	$7.10
Purchase #3	$191.53	4.271%	$199.7102	$199.71	$199.70	$199.70
Purchase #4	$239.67	11.206%	$266.5274	$266.53	$266.55	$266.50
Purchase #5	$22.43	4.718%	$23.4882	$23.49	$23.50	$23.50
Purchase #6	$139.38	12.747%	$157.1468	$157.15	$157.15	$157.10
Purchase #7	$39.98	8.848%	$43.5174	$43.52	$43.50	$43.50
7 purchase totals =	$819.32		$894.3811	$894.39	$894.40	$894.30