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	$215.41	11.478%	$240.1348	$240.13	$240.15	$240.10
Purchase #2	$239.45	11.405%	$266.7593	$266.76	$266.75	$266.80
Purchase #3	$39.34	10.175%	$43.3428	$43.34	$43.35	$43.30
Purchase #4	$33.89	11.296%	$37.7182	$37.72	$37.70	$37.70
Purchase #5	$250.27	13.705%	$284.5695	$284.57	$284.55	$284.60
Purchase #6	$231.28	13.293%	$262.0241	$262.02	$262.00	$262.00
Purchase #7	$250.28	12.615%	$281.8528	$281.85	$281.85	$281.90
7 purchase totals =	$1,259.92		$1,416.4015	$1,416.39	$1,416.35	$1,416.40