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	$132.67	13.471%	$150.542	$150.54	$150.55	$150.50
Purchase #2	$50.93	7.405%	$54.7014	$54.70	$54.70	$54.70
Purchase #3	$230.93	4.452%	$241.211	$241.21	$241.20	$241.20
Purchase #4	$212.70	11.243%	$236.6139	$236.61	$236.60	$236.60
Purchase #5	$95.48	8.439%	$103.5376	$103.54	$103.55	$103.50
Purchase #6	$128.60	9.109%	$140.3142	$140.31	$140.30	$140.30
Purchase #7	$215.31	6.296%	$228.8659	$228.87	$228.85	$228.90
7 purchase totals =	$1,066.62		$1,155.7860	$1,155.78	$1,155.75	$1,155.70