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	$184.28	11.140%	$204.8088	$204.81	$204.80	$204.80
Purchase #2	$53.81	10.540%	$59.4816	$59.48	$59.50	$59.50
Purchase #3	$151.55	7.487%	$162.8965	$162.90	$162.90	$162.90
Purchase #4	$208.26	10.832%	$230.8187	$230.82	$230.80	$230.80
Purchase #5	$11.65	9.768%	$12.788	$12.79	$12.80	$12.80
Purchase #6	$213.79	4.666%	$223.7654	$223.77	$223.75	$223.80
Purchase #7	$139.83	13.499%	$158.7057	$158.71	$158.70	$158.70
7 purchase totals =	$963.17		$1,053.2647	$1,053.28	$1,053.25	$1,053.30