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	$128.63	11.271%	$143.1279	$143.13	$143.15	$143.10
Purchase #2	$116.85	5.518%	$123.2978	$123.30	$123.30	$123.30
Purchase #3	$149.47	3.374%	$154.5131	$154.51	$154.50	$154.50
Purchase #4	$157.72	8.123%	$170.5316	$170.53	$170.55	$170.50
Purchase #5	$94.38	4.666%	$98.7838	$98.78	$98.80	$98.80
Purchase #6	$154.64	13.221%	$175.085	$175.09	$175.10	$175.10
Purchase #7	$28.37	11.209%	$31.55	$31.55	$31.55	$31.60
7 purchase totals =	$830.06		$896.8892	$896.89	$896.95	$896.90