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	$100.95	10.236%	$111.2832	$111.28	$111.30	$111.30
Purchase #2	$175.27	10.314%	$193.3473	$193.35	$193.35	$193.30
Purchase #3	$213.76	3.698%	$221.6648	$221.66	$221.65	$221.70
Purchase #4	$106.36	3.576%	$110.1634	$110.16	$110.15	$110.20
Purchase #5	$224.99	8.196%	$243.4302	$243.43	$243.45	$243.40
Purchase #6	$94.48	6.388%	$100.5154	$100.52	$100.50	$100.50
Purchase #7	$31.65	8.510%	$34.3434	$34.34	$34.35	$34.30
7 purchase totals =	$947.46		$1,014.7477	$1,014.74	$1,014.75	$1,014.70