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	$97.27	8.754%	$105.785	$105.79	$105.80	$105.80
Purchase #2	$134.32	12.755%	$151.4525	$151.45	$151.45	$151.50
Purchase #3	$67.50	12.416%	$75.8808	$75.88	$75.90	$75.90
Purchase #4	$230.95	10.458%	$255.1028	$255.10	$255.10	$255.10
Purchase #5	$246.61	8.406%	$267.34	$267.34	$267.35	$267.30
Purchase #6	$110.30	5.829%	$116.7294	$116.73	$116.75	$116.70
Purchase #7	$40.43	4.422%	$42.2178	$42.22	$42.20	$42.20
7 purchase totals =	$927.38		$1,014.5083	$1,014.51	$1,014.55	$1,014.50