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	$175.80	12.315%	$197.4498	$197.45	$197.45	$197.40
Purchase #2	$210.60	5.525%	$222.2357	$222.24	$222.25	$222.20
Purchase #3	$172.71	7.644%	$185.912	$185.91	$185.90	$185.90
Purchase #4	$194.95	11.238%	$216.8585	$216.86	$216.85	$216.90
Purchase #5	$214.58	4.252%	$223.7039	$223.70	$223.70	$223.70
Purchase #6	$244.47	5.309%	$257.4489	$257.45	$257.45	$257.40
Purchase #7	$233.75	11.166%	$259.8505	$259.85	$259.85	$259.90
7 purchase totals =	$1,446.86		$1,563.4593	$1,563.46	$1,563.45	$1,563.40