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	$93.95	12.623%	$105.8093	$105.81	$105.80	$105.80
Purchase #2	$238.63	6.325%	$253.7233	$253.72	$253.70	$253.70
Purchase #3	$209.28	6.531%	$222.9481	$222.95	$222.95	$222.90
Purchase #4	$235.83	5.103%	$247.8644	$247.86	$247.85	$247.90
Purchase #5	$189.41	4.488%	$197.9107	$197.91	$197.90	$197.90
Purchase #6	$67.44	5.317%	$71.0258	$71.03	$71.05	$71.00
Purchase #7	$77.75	11.340%	$86.5669	$86.57	$86.55	$86.60
7 purchase totals =	$1,112.29		$1,185.8485	$1,185.85	$1,185.80	$1,185.80