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	$92.56	3.580%	$95.8736	$95.87	$95.85	$95.90
Purchase #2	$104.96	3.524%	$108.6588	$108.66	$108.65	$108.70
Purchase #3	$66.38	13.413%	$75.2835	$75.28	$75.30	$75.30
Purchase #4	$149.69	6.388%	$159.2522	$159.25	$159.25	$159.30
Purchase #5	$115.28	8.851%	$125.4834	$125.48	$125.50	$125.50
Purchase #6	$17.49	11.424%	$19.4881	$19.49	$19.50	$19.50
Purchase #7	$78.53	6.294%	$83.4727	$83.47	$83.45	$83.50
7 purchase totals =	$624.89		$667.5123	$667.50	$667.50	$667.70