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	$141.89	7.733%	$152.8624	$152.86	$152.85	$152.90
Purchase #2	$125.66	4.473%	$131.2808	$131.28	$131.30	$131.30
Purchase #3	$141.49	5.797%	$149.6922	$149.69	$149.70	$149.70
Purchase #4	$126.61	12.845%	$142.8731	$142.87	$142.85	$142.90
Purchase #5	$55.86	9.327%	$61.0701	$61.07	$61.05	$61.10
Purchase #6	$180.74	5.134%	$190.0192	$190.02	$190.00	$190.00
Purchase #7	$179.79	6.749%	$191.924	$191.92	$191.90	$191.90
7 purchase totals =	$952.04		$1,019.7218	$1,019.71	$1,019.65	$1,019.80