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	$117.44	11.340%	$130.7577	$130.76	$130.75	$130.80
Purchase #2	$123.68	5.197%	$130.1076	$130.11	$130.10	$130.10
Purchase #3	$9.70	5.469%	$10.2305	$10.23	$10.25	$10.20
Purchase #4	$135.49	6.661%	$144.515	$144.52	$144.50	$144.50
Purchase #5	$175.93	7.866%	$189.7687	$189.77	$189.75	$189.80
Purchase #6	$92.27	8.749%	$100.3427	$100.34	$100.35	$100.30
Purchase #7	$54.90	8.809%	$59.7361	$59.74	$59.75	$59.70
7 purchase totals =	$709.41		$765.4583	$765.47	$765.45	$765.40