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	$184.76	8.542%	$200.5422	$200.54	$200.55	$200.50
Purchase #2	$223.27	4.695%	$233.7525	$233.75	$233.75	$233.80
Purchase #3	$159.45	9.812%	$175.0952	$175.10	$175.10	$175.10
Purchase #4	$149.30	6.320%	$158.7358	$158.74	$158.75	$158.70
Purchase #5	$141.73	6.695%	$151.2188	$151.22	$151.20	$151.20
Purchase #6	$143.98	6.170%	$152.8636	$152.86	$152.85	$152.90
Purchase #7	$126.52	10.542%	$139.8577	$139.86	$139.85	$139.90
7 purchase totals =	$1,129.01		$1,212.0658	$1,212.07	$1,212.05	$1,212.10