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	$140.78	5.664%	$148.7538	$148.75	$148.75	$148.80
Purchase #2	$52.68	5.558%	$55.608	$55.61	$55.60	$55.60
Purchase #3	$232.95	8.870%	$253.6127	$253.61	$253.60	$253.60
Purchase #4	$151.28	4.856%	$158.6262	$158.63	$158.65	$158.60
Purchase #5	$34.72	13.580%	$39.435	$39.44	$39.45	$39.40
Purchase #6	$120.38	5.540%	$127.0491	$127.05	$127.05	$127.00
Purchase #7	$221.69	8.455%	$240.4339	$240.43	$240.45	$240.40
7 purchase totals =	$954.48		$1,023.5187	$1,023.52	$1,023.55	$1,023.40