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	$62.28	4.456%	$65.0552	$65.06	$65.05	$65.10
Purchase #2	$66.72	7.410%	$71.664	$71.66	$71.65	$71.70
Purchase #3	$116.58	9.697%	$127.8848	$127.88	$127.90	$127.90
Purchase #4	$157.81	5.571%	$166.6016	$166.60	$166.60	$166.60
Purchase #5	$36.83	6.703%	$39.2987	$39.30	$39.30	$39.30
Purchase #6	$220.26	10.179%	$242.6803	$242.68	$242.70	$242.70
Purchase #7	$109.26	4.758%	$114.4586	$114.46	$114.45	$114.50
7 purchase totals =	$769.74		$827.6432	$827.64	$827.65	$827.80