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	$119.34	4.848%	$125.1256	$125.13	$125.15	$125.10
Purchase #2	$15.83	11.520%	$17.6536	$17.65	$17.65	$17.70
Purchase #3	$80.86	10.175%	$89.0875	$89.09	$89.10	$89.10
Purchase #4	$148.54	4.313%	$154.9465	$154.95	$154.95	$154.90
Purchase #5	$128.77	10.843%	$142.7325	$142.73	$142.75	$142.70
Purchase #6	$184.68	6.599%	$196.867	$196.87	$196.85	$196.90
Purchase #7	$129.62	7.531%	$139.3817	$139.38	$139.40	$139.40
7 purchase totals =	$807.64		$865.7944	$865.80	$865.85	$865.80