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	$60.59	8.293%	$65.6147	$65.61	$65.60	$65.60
Purchase #2	$184.63	6.535%	$196.6956	$196.70	$196.70	$196.70
Purchase #3	$148.52	8.646%	$161.361	$161.36	$161.35	$161.40
Purchase #4	$77.92	8.419%	$84.4801	$84.48	$84.50	$84.50
Purchase #5	$158.33	8.575%	$171.9068	$171.91	$171.90	$171.90
Purchase #6	$90.97	9.527%	$99.6367	$99.64	$99.65	$99.60
Purchase #7	$247.90	7.443%	$266.3512	$266.35	$266.35	$266.40
7 purchase totals =	$968.86		$1,046.0461	$1,046.05	$1,046.05	$1,046.10