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	$97.61	3.533%	$101.0586	$101.06	$101.05	$101.10
Purchase #2	$69.59	13.230%	$78.7968	$78.80	$78.80	$78.80
Purchase #3	$140.37	11.749%	$156.8621	$156.86	$156.85	$156.90
Purchase #4	$23.83	3.395%	$24.639	$24.64	$24.65	$24.60
Purchase #5	$97.60	13.182%	$110.4656	$110.47	$110.45	$110.50
Purchase #6	$127.49	11.185%	$141.7498	$141.75	$141.75	$141.70
Purchase #7	$112.57	5.247%	$118.4765	$118.48	$118.50	$118.50
7 purchase totals =	$669.06		$732.0484	$732.06	$732.05	$732.10