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	$208.25	3.220%	$214.9557	$214.96	$214.95	$215.00
Purchase #2	$91.76	9.417%	$100.401	$100.40	$100.40	$100.40
Purchase #3	$137.66	13.631%	$156.4244	$156.42	$156.40	$156.40
Purchase #4	$104.58	4.692%	$109.4869	$109.49	$109.50	$109.50
Purchase #5	$56.89	5.416%	$59.9712	$59.97	$59.95	$60.00
Purchase #6	$235.28	11.554%	$262.4643	$262.46	$262.45	$262.50
Purchase #7	$73.56	11.335%	$81.898	$81.90	$81.90	$81.90
7 purchase totals =	$907.98		$985.6015	$985.60	$985.55	$985.70