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	$152.84	7.660%	$164.5475	$164.55	$164.55	$164.50
Purchase #2	$32.51	4.722%	$34.0451	$34.05	$34.05	$34.00
Purchase #3	$28.31	7.749%	$30.5037	$30.50	$30.50	$30.50
Purchase #4	$15.29	13.511%	$17.3558	$17.36	$17.35	$17.40
Purchase #5	$137.74	10.633%	$152.3859	$152.39	$152.40	$152.40
Purchase #6	$242.81	10.151%	$267.4576	$267.46	$267.45	$267.50
Purchase #7	$53.52	11.566%	$59.7101	$59.71	$59.70	$59.70
7 purchase totals =	$663.02		$726.0057	$726.02	$726.00	$726.00