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	$179.46	6.864%	$191.7781	$191.78	$191.80	$191.80
Purchase #2	$53.38	11.492%	$59.5144	$59.51	$59.50	$59.50
Purchase #3	$97.45	8.635%	$105.8648	$105.86	$105.85	$105.90
Purchase #4	$182.73	11.623%	$203.9687	$203.97	$203.95	$204.00
Purchase #5	$176.92	10.512%	$195.5178	$195.52	$195.50	$195.50
Purchase #6	$157.70	7.134%	$168.9503	$168.95	$168.95	$169.00
Purchase #7	$177.90	5.422%	$187.5457	$187.55	$187.55	$187.50
7 purchase totals =	$1,025.54		$1,113.1398	$1,113.14	$1,113.10	$1,113.20