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	$174.67	4.107%	$181.8437	$181.84	$181.85	$181.80
Purchase #2	$182.54	5.553%	$192.6764	$192.68	$192.70	$192.70
Purchase #3	$174.92	10.389%	$193.0924	$193.09	$193.10	$193.10
Purchase #4	$175.78	11.574%	$196.1248	$196.12	$196.10	$196.10
Purchase #5	$11.47	5.572%	$12.1091	$12.11	$12.10	$12.10
Purchase #6	$226.27	13.114%	$255.943	$255.94	$255.95	$255.90
Purchase #7	$179.46	6.272%	$190.7157	$190.72	$190.70	$190.70
7 purchase totals =	$1,125.11		$1,222.5051	$1,222.50	$1,222.50	$1,222.40