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	$162.95	11.694%	$182.0054	$182.01	$182.00	$182.00
Purchase #2	$140.76	8.346%	$152.5078	$152.51	$152.50	$152.50
Purchase #3	$187.70	6.733%	$200.3378	$200.34	$200.35	$200.30
Purchase #4	$47.50	7.265%	$50.9509	$50.95	$50.95	$51.00
Purchase #5	$131.68	9.167%	$143.7511	$143.75	$143.75	$143.80
Purchase #6	$178.56	6.191%	$189.6146	$189.61	$189.60	$189.60
Purchase #7	$13.55	7.138%	$14.5172	$14.52	$14.50	$14.50
7 purchase totals =	$862.70		$933.6848	$933.69	$933.65	$933.70