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	$151.68	11.605%	$169.2825	$169.28	$169.30	$169.30
Purchase #2	$52.28	4.534%	$54.6504	$54.65	$54.65	$54.70
Purchase #3	$146.58	9.543%	$160.5681	$160.57	$160.55	$160.60
Purchase #4	$242.31	5.848%	$256.4803	$256.48	$256.50	$256.50
Purchase #5	$196.31	10.292%	$216.5142	$216.51	$216.50	$216.50
Purchase #6	$227.57	3.581%	$235.7193	$235.72	$235.70	$235.70
Purchase #7	$38.43	7.109%	$41.162	$41.16	$41.15	$41.20
7 purchase totals =	$1,055.16		$1,134.3768	$1,134.37	$1,134.35	$1,134.50