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	$220.89	6.783%	$235.873	$235.87	$235.85	$235.90
Purchase #2	$69.48	4.654%	$72.7136	$72.71	$72.70	$72.70
Purchase #3	$222.34	10.488%	$245.659	$245.66	$245.65	$245.70
Purchase #4	$139.78	5.128%	$146.9479	$146.95	$146.95	$146.90
Purchase #5	$95.63	4.265%	$99.7086	$99.71	$99.70	$99.70
Purchase #6	$28.38	3.709%	$29.4326	$29.43	$29.45	$29.40
Purchase #7	$41.59	13.696%	$47.2862	$47.29	$47.30	$47.30
7 purchase totals =	$818.09		$877.6209	$877.62	$877.60	$877.60