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	$160.94	9.190%	$175.7304	$175.73	$175.75	$175.70
Purchase #2	$123.88	5.338%	$130.4927	$130.49	$130.50	$130.50
Purchase #3	$241.39	11.716%	$269.6713	$269.67	$269.65	$269.70
Purchase #4	$196.57	7.266%	$210.8528	$210.85	$210.85	$210.90
Purchase #5	$58.48	6.741%	$62.4221	$62.42	$62.40	$62.40
Purchase #6	$117.88	7.647%	$126.8943	$126.89	$126.90	$126.90
Purchase #7	$181.35	8.382%	$196.5508	$196.55	$196.55	$196.60
7 purchase totals =	$1,080.49		$1,172.6144	$1,172.60	$1,172.60	$1,172.70