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	$196.63	8.229%	$212.8107	$212.81	$212.80	$212.80
Purchase #2	$50.97	12.475%	$57.3285	$57.33	$57.35	$57.30
Purchase #3	$85.51	8.433%	$92.7211	$92.72	$92.70	$92.70
Purchase #4	$229.37	11.433%	$255.5939	$255.59	$255.60	$255.60
Purchase #5	$228.78	13.724%	$260.1778	$260.18	$260.20	$260.20
Purchase #6	$179.37	6.738%	$191.456	$191.46	$191.45	$191.50
Purchase #7	$223.38	7.234%	$239.5393	$239.54	$239.55	$239.50
7 purchase totals =	$1,194.01		$1,309.6273	$1,309.63	$1,309.65	$1,309.60