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	$216.47	8.802%	$235.5237	$235.52	$235.50	$235.50
Purchase #2	$114.61	8.146%	$123.9461	$123.95	$123.95	$123.90
Purchase #3	$80.95	11.255%	$90.0609	$90.06	$90.05	$90.10
Purchase #4	$47.32	11.484%	$52.7542	$52.75	$52.75	$52.80
Purchase #5	$162.64	13.616%	$184.7851	$184.79	$184.80	$184.80
Purchase #6	$160.56	8.191%	$173.7115	$173.71	$173.70	$173.70
Purchase #7	$240.68	9.199%	$262.8202	$262.82	$262.80	$262.80
7 purchase totals =	$1,023.23		$1,123.6017	$1,123.60	$1,123.55	$1,123.60