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	$181.90	8.127%	$196.683	$196.68	$196.70	$196.70
Purchase #2	$140.83	6.853%	$150.4811	$150.48	$150.50	$150.50
Purchase #3	$145.43	12.335%	$163.3688	$163.37	$163.35	$163.40
Purchase #4	$9.68	10.647%	$10.7106	$10.71	$10.70	$10.70
Purchase #5	$13.95	5.114%	$14.6634	$14.66	$14.65	$14.70
Purchase #6	$99.38	10.285%	$109.6012	$109.60	$109.60	$109.60
Purchase #7	$114.29	12.511%	$128.5888	$128.59	$128.60	$128.60
7 purchase totals =	$705.46		$774.0969	$774.09	$774.10	$774.20