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	$95.93	10.296%	$105.807	$105.81	$105.80	$105.80
Purchase #2	$136.78	12.577%	$153.9828	$153.98	$154.00	$154.00
Purchase #3	$55.61	9.502%	$60.8941	$60.89	$60.90	$60.90
Purchase #4	$156.78	11.332%	$174.5463	$174.55	$174.55	$174.50
Purchase #5	$159.62	12.256%	$179.183	$179.18	$179.20	$179.20
Purchase #6	$106.32	7.496%	$114.2897	$114.29	$114.30	$114.30
Purchase #7	$109.89	3.822%	$114.09	$114.09	$114.10	$114.10
7 purchase totals =	$820.93		$902.7929	$902.79	$902.85	$902.80