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	$103.78	9.860%	$114.0127	$114.01	$114.00	$114.00
Purchase #2	$103.86	10.252%	$114.5077	$114.51	$114.50	$114.50
Purchase #3	$204.67	8.698%	$222.4722	$222.47	$222.45	$222.50
Purchase #4	$99.92	3.105%	$103.0225	$103.02	$103.00	$103.00
Purchase #5	$194.49	3.787%	$201.8553	$201.86	$201.85	$201.90
Purchase #6	$155.72	6.451%	$165.7655	$165.77	$165.75	$165.80
Purchase #7	$61.27	10.808%	$67.8921	$67.89	$67.90	$67.90
7 purchase totals =	$923.71		$989.5280	$989.53	$989.45	$989.60