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	$197.90	6.179%	$210.1282	$210.13	$210.15	$210.10
Purchase #2	$197.44	12.864%	$222.8387	$222.84	$222.85	$222.80
Purchase #3	$196.83	6.147%	$208.9291	$208.93	$208.95	$208.90
Purchase #4	$94.94	5.479%	$100.1418	$100.14	$100.15	$100.10
Purchase #5	$63.59	5.513%	$67.0957	$67.10	$67.10	$67.10
Purchase #6	$149.37	6.302%	$158.7833	$158.78	$158.80	$158.80
Purchase #7	$180.75	10.383%	$199.5173	$199.52	$199.50	$199.50
7 purchase totals =	$1,080.82		$1,167.4341	$1,167.44	$1,167.50	$1,167.30