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	$174.89	9.133%	$190.8627	$190.86	$190.85	$190.90
Purchase #2	$10.57	9.860%	$11.6122	$11.61	$11.60	$11.60
Purchase #3	$33.69	11.593%	$37.5957	$37.60	$37.60	$37.60
Purchase #4	$99.29	6.139%	$105.3854	$105.39	$105.40	$105.40
Purchase #5	$135.85	5.692%	$143.5826	$143.58	$143.60	$143.60
Purchase #6	$47.44	9.223%	$51.8154	$51.82	$51.80	$51.80
Purchase #7	$245.62	5.803%	$259.8733	$259.87	$259.85	$259.90
7 purchase totals =	$747.35		$800.7273	$800.73	$800.70	$800.80