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	$99.39	7.553%	$106.8969	$106.90	$106.90	$106.90
Purchase #2	$100.96	4.219%	$105.2195	$105.22	$105.20	$105.20
Purchase #3	$85.77	5.567%	$90.5448	$90.54	$90.55	$90.50
Purchase #4	$182.45	6.777%	$194.8146	$194.81	$194.80	$194.80
Purchase #5	$245.51	4.477%	$256.5015	$256.50	$256.50	$256.50
Purchase #6	$211.63	3.843%	$219.7629	$219.76	$219.75	$219.80
Purchase #7	$53.72	12.201%	$60.2744	$60.27	$60.25	$60.30
7 purchase totals =	$979.43		$1,034.0146	$1,034.00	$1,033.95	$1,034.00