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	$162.67	12.214%	$182.5385	$182.54	$182.55	$182.50
Purchase #2	$100.40	10.630%	$111.0725	$111.07	$111.05	$111.10
Purchase #3	$104.55	3.560%	$108.272	$108.27	$108.25	$108.30
Purchase #4	$111.51	12.434%	$125.3752	$125.38	$125.40	$125.40
Purchase #5	$223.85	10.540%	$247.4438	$247.44	$247.45	$247.40
Purchase #6	$105.34	13.658%	$119.7273	$119.73	$119.75	$119.70
Purchase #7	$149.74	5.208%	$157.5385	$157.54	$157.55	$157.50
7 purchase totals =	$958.06		$1,051.9678	$1,051.97	$1,052.00	$1,051.90