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	$175.92	13.532%	$199.7255	$199.73	$199.75	$199.70
Purchase #2	$166.48	5.676%	$175.9294	$175.93	$175.95	$175.90
Purchase #3	$10.41	9.612%	$11.4106	$11.41	$11.40	$11.40
Purchase #4	$93.60	11.864%	$104.7047	$104.70	$104.70	$104.70
Purchase #5	$55.29	8.163%	$59.8033	$59.80	$59.80	$59.80
Purchase #6	$91.51	4.364%	$95.5035	$95.50	$95.50	$95.50
Purchase #7	$85.68	4.117%	$89.2074	$89.21	$89.20	$89.20
7 purchase totals =	$678.89		$736.2844	$736.28	$736.30	$736.20