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	$186.53	13.498%	$211.7078	$211.71	$211.70	$211.70
Purchase #2	$224.39	13.754%	$255.2526	$255.25	$255.25	$255.30
Purchase #3	$132.46	8.220%	$143.3482	$143.35	$143.35	$143.30
Purchase #4	$58.72	13.637%	$66.7276	$66.73	$66.75	$66.70
Purchase #5	$78.86	8.304%	$85.4085	$85.41	$85.40	$85.40
Purchase #6	$157.61	4.293%	$164.3762	$164.38	$164.40	$164.40
Purchase #7	$158.96	11.518%	$177.269	$177.27	$177.25	$177.30
7 purchase totals =	$997.53		$1,104.0899	$1,104.10	$1,104.10	$1,104.10