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	$157.33	5.346%	$165.7409	$165.74	$165.75	$165.70
Purchase #2	$241.49	6.612%	$257.4573	$257.46	$257.45	$257.50
Purchase #3	$104.88	3.786%	$108.8508	$108.85	$108.85	$108.90
Purchase #4	$208.68	6.417%	$222.071	$222.07	$222.05	$222.10
Purchase #5	$95.51	4.336%	$99.6513	$99.65	$99.65	$99.70
Purchase #6	$10.41	5.468%	$10.9792	$10.98	$11.00	$11.00
Purchase #7	$185.96	4.596%	$194.5067	$194.51	$194.50	$194.50
7 purchase totals =	$1,004.26		$1,059.2572	$1,059.26	$1,059.25	$1,059.40