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	$96.64	10.417%	$106.707	$106.71	$106.70	$106.70
Purchase #2	$236.96	10.679%	$262.265	$262.27	$262.25	$262.30
Purchase #3	$75.94	13.546%	$86.2268	$86.23	$86.25	$86.20
Purchase #4	$67.62	6.107%	$71.7496	$71.75	$71.75	$71.70
Purchase #5	$118.34	12.227%	$132.8094	$132.81	$132.80	$132.80
Purchase #6	$186.64	5.313%	$196.5562	$196.56	$196.55	$196.60
Purchase #7	$183.36	4.216%	$191.0905	$191.09	$191.10	$191.10
7 purchase totals =	$965.50		$1,047.4045	$1,047.42	$1,047.40	$1,047.40