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	$200.73	7.529%	$215.843	$215.84	$215.85	$215.80
Purchase #2	$100.48	4.749%	$105.2518	$105.25	$105.25	$105.30
Purchase #3	$203.93	4.463%	$213.0314	$213.03	$213.05	$213.00
Purchase #4	$42.87	8.460%	$46.4968	$46.50	$46.50	$46.50
Purchase #5	$178.26	11.686%	$199.0915	$199.09	$199.10	$199.10
Purchase #6	$151.92	4.245%	$158.369	$158.37	$158.35	$158.40
Purchase #7	$131.63	8.259%	$142.5013	$142.50	$142.50	$142.50
7 purchase totals =	$1,009.82		$1,080.5848	$1,080.58	$1,080.60	$1,080.60