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	$190.74	7.330%	$204.7212	$204.72	$204.70	$204.70
Purchase #2	$228.63	10.842%	$253.4181	$253.42	$253.40	$253.40
Purchase #3	$193.58	10.277%	$213.4742	$213.47	$213.45	$213.50
Purchase #4	$100.63	8.481%	$109.1644	$109.16	$109.15	$109.20
Purchase #5	$189.93	5.536%	$200.4445	$200.44	$200.45	$200.40
Purchase #6	$19.83	7.208%	$21.2593	$21.26	$21.25	$21.30
Purchase #7	$139.95	4.362%	$146.0546	$146.05	$146.05	$146.10
7 purchase totals =	$1,063.29		$1,148.5363	$1,148.52	$1,148.45	$1,148.60