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	$196.93	5.853%	$208.4563	$208.46	$208.45	$208.50
Purchase #2	$85.72	9.509%	$93.8711	$93.87	$93.85	$93.90
Purchase #3	$205.32	7.465%	$220.6471	$220.65	$220.65	$220.60
Purchase #4	$233.63	13.309%	$264.7238	$264.72	$264.70	$264.70
Purchase #5	$193.97	7.271%	$208.0736	$208.07	$208.05	$208.10
Purchase #6	$9.38	13.106%	$10.6093	$10.61	$10.60	$10.60
Purchase #7	$88.74	12.198%	$99.5645	$99.56	$99.55	$99.60
7 purchase totals =	$1,013.69		$1,105.9457	$1,105.94	$1,105.85	$1,106.00