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	$217.73	5.106%	$228.8473	$228.85	$228.85	$228.80
Purchase #2	$93.87	12.654%	$105.7483	$105.75	$105.75	$105.70
Purchase #3	$189.76	3.727%	$196.8324	$196.83	$196.85	$196.80
Purchase #4	$167.60	6.441%	$178.3951	$178.40	$178.40	$178.40
Purchase #5	$61.93	12.866%	$69.8979	$69.90	$69.90	$69.90
Purchase #6	$58.89	4.211%	$61.3699	$61.37	$61.35	$61.40
Purchase #7	$189.70	13.156%	$214.6569	$214.66	$214.65	$214.70
7 purchase totals =	$979.48		$1,055.7478	$1,055.76	$1,055.75	$1,055.70