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	$195.64	9.493%	$214.2121	$214.21	$214.20	$214.20
Purchase #2	$53.59	13.646%	$60.9029	$60.90	$60.90	$60.90
Purchase #3	$80.43	3.774%	$83.4654	$83.47	$83.45	$83.50
Purchase #4	$184.48	6.421%	$196.3255	$196.33	$196.35	$196.30
Purchase #5	$34.60	12.337%	$38.8686	$38.87	$38.85	$38.90
Purchase #6	$214.39	5.250%	$225.6455	$225.65	$225.65	$225.60
Purchase #7	$209.40	13.792%	$238.2804	$238.28	$238.30	$238.30
7 purchase totals =	$972.53		$1,057.7004	$1,057.71	$1,057.70	$1,057.70