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	$196.35	13.398%	$222.657	$222.66	$222.65	$222.70
Purchase #2	$231.31	5.356%	$243.699	$243.70	$243.70	$243.70
Purchase #3	$39.94	6.692%	$42.6128	$42.61	$42.60	$42.60
Purchase #4	$44.81	8.137%	$48.4562	$48.46	$48.45	$48.50
Purchase #5	$193.70	11.229%	$215.4506	$215.45	$215.45	$215.50
Purchase #6	$123.80	3.286%	$127.8681	$127.87	$127.85	$127.90
Purchase #7	$245.38	12.206%	$275.3311	$275.33	$275.35	$275.30
7 purchase totals =	$1,075.29		$1,176.0748	$1,176.08	$1,176.05	$1,176.20