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	$194.42	5.743%	$205.5855	$205.59	$205.60	$205.60
Purchase #2	$146.90	6.465%	$156.3971	$156.40	$156.40	$156.40
Purchase #3	$212.63	4.532%	$222.2664	$222.27	$222.25	$222.30
Purchase #4	$51.68	6.575%	$55.078	$55.08	$55.10	$55.10
Purchase #5	$221.83	6.603%	$236.4774	$236.48	$236.50	$236.50
Purchase #6	$169.29	12.510%	$190.4682	$190.47	$190.45	$190.50
Purchase #7	$78.86	9.543%	$86.3856	$86.39	$86.40	$86.40
7 purchase totals =	$1,075.61		$1,152.6582	$1,152.68	$1,152.70	$1,152.80