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	$179.48	3.431%	$185.638	$185.64	$185.65	$185.60
Purchase #2	$28.26	12.333%	$31.7453	$31.75	$31.75	$31.70
Purchase #3	$73.30	5.240%	$77.1409	$77.14	$77.15	$77.10
Purchase #4	$85.47	11.350%	$95.1708	$95.17	$95.15	$95.20
Purchase #5	$99.67	12.732%	$112.36	$112.36	$112.35	$112.40
Purchase #6	$70.62	11.193%	$78.5245	$78.52	$78.50	$78.50
Purchase #7	$157.56	3.102%	$162.4475	$162.45	$162.45	$162.40
7 purchase totals =	$694.36		$743.0270	$743.03	$743.00	$742.90