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	$206.62	7.659%	$222.445	$222.45	$222.45	$222.40
Purchase #2	$16.55	13.288%	$18.7492	$18.75	$18.75	$18.70
Purchase #3	$81.64	12.567%	$91.8997	$91.90	$91.90	$91.90
Purchase #4	$24.52	4.665%	$25.6639	$25.66	$25.65	$25.70
Purchase #5	$99.88	5.689%	$105.5622	$105.56	$105.55	$105.60
Purchase #6	$14.77	3.433%	$15.2771	$15.28	$15.30	$15.30
Purchase #7	$134.58	9.866%	$147.8577	$147.86	$147.85	$147.90
7 purchase totals =	$578.56		$627.4548	$627.46	$627.45	$627.50