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	$55.71	8.477%	$60.4325	$60.43	$60.45	$60.40
Purchase #2	$128.53	10.229%	$141.6773	$141.68	$141.70	$141.70
Purchase #3	$53.59	10.857%	$59.4083	$59.41	$59.40	$59.40
Purchase #4	$175.77	11.537%	$196.0486	$196.05	$196.05	$196.00
Purchase #5	$174.91	6.694%	$186.6185	$186.62	$186.60	$186.60
Purchase #6	$249.89	5.199%	$262.8818	$262.88	$262.90	$262.90
Purchase #7	$148.25	8.227%	$160.4465	$160.45	$160.45	$160.40
7 purchase totals =	$986.65		$1,067.5135	$1,067.52	$1,067.55	$1,067.40