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	$200.32	8.463%	$217.2731	$217.27	$217.25	$217.30
Purchase #2	$201.76	8.486%	$218.8814	$218.88	$218.90	$218.90
Purchase #3	$70.45	13.265%	$79.7952	$79.80	$79.80	$79.80
Purchase #4	$92.26	9.359%	$100.8946	$100.89	$100.90	$100.90
Purchase #5	$249.81	5.123%	$262.6078	$262.61	$262.60	$262.60
Purchase #6	$108.50	6.700%	$115.7695	$115.77	$115.75	$115.80
Purchase #7	$62.83	6.715%	$67.049	$67.05	$67.05	$67.00
7 purchase totals =	$985.93		$1,062.2706	$1,062.27	$1,062.25	$1,062.30