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	$112.72	12.514%	$126.8258	$126.83	$126.85	$126.80
Purchase #2	$29.92	12.781%	$33.7441	$33.74	$33.75	$33.70
Purchase #3	$124.55	5.445%	$131.3317	$131.33	$131.35	$131.30
Purchase #4	$214.32	4.322%	$223.5829	$223.58	$223.60	$223.60
Purchase #5	$191.89	10.797%	$212.6084	$212.61	$212.60	$212.60
Purchase #6	$208.86	10.856%	$231.5338	$231.53	$231.55	$231.50
Purchase #7	$131.27	11.172%	$145.9355	$145.94	$145.95	$145.90
7 purchase totals =	$1,013.53		$1,105.5622	$1,105.56	$1,105.65	$1,105.40