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	$176.47	4.348%	$184.1429	$184.14	$184.15	$184.10
Purchase #2	$167.25	3.497%	$173.0987	$173.10	$173.10	$173.10
Purchase #3	$221.33	3.405%	$228.8663	$228.87	$228.85	$228.90
Purchase #4	$82.39	5.318%	$86.7715	$86.77	$86.75	$86.80
Purchase #5	$100.67	10.355%	$111.0944	$111.09	$111.10	$111.10
Purchase #6	$11.66	10.290%	$12.8598	$12.86	$12.85	$12.90
Purchase #7	$139.98	3.265%	$144.5503	$144.55	$144.55	$144.60
7 purchase totals =	$899.75		$941.3839	$941.38	$941.35	$941.50