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	$117.66	10.805%	$130.3732	$130.37	$130.35	$130.40
Purchase #2	$132.44	13.694%	$150.5763	$150.58	$150.60	$150.60
Purchase #3	$75.59	6.793%	$80.7248	$80.72	$80.70	$80.70
Purchase #4	$207.35	6.735%	$221.315	$221.32	$221.30	$221.30
Purchase #5	$240.81	5.284%	$253.5344	$253.53	$253.55	$253.50
Purchase #6	$32.76	5.322%	$34.5035	$34.50	$34.50	$34.50
Purchase #7	$179.84	9.265%	$196.5022	$196.50	$196.50	$196.50
7 purchase totals =	$986.45		$1,067.5294	$1,067.52	$1,067.50	$1,067.50