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	$162.69	11.453%	$181.3229	$181.32	$181.30	$181.30
Purchase #2	$213.47	3.547%	$221.0418	$221.04	$221.05	$221.00
Purchase #3	$247.55	7.618%	$266.4084	$266.41	$266.40	$266.40
Purchase #4	$239.60	11.239%	$266.5286	$266.53	$266.55	$266.50
Purchase #5	$100.85	4.117%	$105.002	$105.00	$105.00	$105.00
Purchase #6	$23.38	6.453%	$24.8887	$24.89	$24.90	$24.90
Purchase #7	$59.88	12.650%	$67.4548	$67.45	$67.45	$67.50
7 purchase totals =	$1,047.42		$1,132.6472	$1,132.64	$1,132.65	$1,132.60