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	$62.34	11.614%	$69.5802	$69.58	$69.60	$69.60
Purchase #2	$61.40	4.593%	$64.2201	$64.22	$64.20	$64.20
Purchase #3	$245.34	4.224%	$255.7032	$255.70	$255.70	$255.70
Purchase #4	$100.68	5.230%	$105.9456	$105.95	$105.95	$105.90
Purchase #5	$84.95	12.592%	$95.6469	$95.65	$95.65	$95.60
Purchase #6	$48.55	12.485%	$54.6115	$54.61	$54.60	$54.60
Purchase #7	$102.28	12.385%	$114.9474	$114.95	$114.95	$114.90
7 purchase totals =	$705.54		$760.6549	$760.66	$760.65	$760.50