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	$144.65	9.685%	$158.6594	$158.66	$158.65	$158.70
Purchase #2	$224.60	13.780%	$255.5499	$255.55	$255.55	$255.50
Purchase #3	$150.25	9.860%	$165.0647	$165.06	$165.05	$165.10
Purchase #4	$227.82	4.537%	$238.1562	$238.16	$238.15	$238.20
Purchase #5	$94.59	6.246%	$100.4981	$100.50	$100.50	$100.50
Purchase #6	$134.39	5.688%	$142.0341	$142.03	$142.05	$142.00
Purchase #7	$50.62	5.674%	$53.4922	$53.49	$53.50	$53.50
7 purchase totals =	$1,026.92		$1,113.4546	$1,113.45	$1,113.45	$1,113.50