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	$148.78	6.443%	$158.3659	$158.37	$158.35	$158.40
Purchase #2	$144.27	4.817%	$151.2195	$151.22	$151.20	$151.20
Purchase #3	$134.56	9.812%	$147.763	$147.76	$147.75	$147.80
Purchase #4	$131.76	7.631%	$141.8146	$141.81	$141.80	$141.80
Purchase #5	$10.90	7.646%	$11.7334	$11.73	$11.75	$11.70
Purchase #6	$64.90	9.461%	$71.0402	$71.04	$71.05	$71.00
Purchase #7	$41.46	8.629%	$45.0376	$45.04	$45.05	$45.00
7 purchase totals =	$676.63		$726.9742	$726.97	$726.95	$726.90