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	$157.51	7.841%	$169.8604	$169.86	$169.85	$169.90
Purchase #2	$49.35	9.620%	$54.0975	$54.10	$54.10	$54.10
Purchase #3	$204.25	9.453%	$223.5578	$223.56	$223.55	$223.60
Purchase #4	$114.30	11.107%	$126.9953	$127.00	$127.00	$127.00
Purchase #5	$159.98	5.388%	$168.5997	$168.60	$168.60	$168.60
Purchase #6	$137.53	3.762%	$142.7039	$142.70	$142.70	$142.70
Purchase #7	$126.43	9.362%	$138.2664	$138.27	$138.25	$138.30
7 purchase totals =	$949.35		$1,024.0810	$1,024.09	$1,024.05	$1,024.20