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	$12.57	13.233%	$14.2334	$14.23	$14.25	$14.20
Purchase #2	$122.67	12.208%	$137.6456	$137.65	$137.65	$137.60
Purchase #3	$139.78	6.265%	$148.5372	$148.54	$148.55	$148.50
Purchase #4	$168.80	12.811%	$190.425	$190.43	$190.45	$190.40
Purchase #5	$237.73	11.494%	$265.0547	$265.05	$265.05	$265.10
Purchase #6	$174.71	9.235%	$190.8445	$190.84	$190.85	$190.80
Purchase #7	$60.62	6.111%	$64.3245	$64.32	$64.30	$64.30
7 purchase totals =	$916.88		$1,011.0649	$1,011.06	$1,011.10	$1,010.90