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	$168.51	13.727%	$191.6414	$191.64	$191.65	$191.60
Purchase #2	$67.83	3.169%	$69.9795	$69.98	$70.00	$70.00
Purchase #3	$12.78	7.348%	$13.7191	$13.72	$13.70	$13.70
Purchase #4	$171.27	11.120%	$190.3152	$190.32	$190.30	$190.30
Purchase #5	$42.47	8.462%	$46.0638	$46.06	$46.05	$46.10
Purchase #6	$138.25	13.475%	$156.8792	$156.88	$156.90	$156.90
Purchase #7	$189.63	10.180%	$208.9343	$208.93	$208.95	$208.90
7 purchase totals =	$790.74		$877.5325	$877.53	$877.55	$877.50