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	$204.38	8.647%	$222.0527	$222.05	$222.05	$222.10
Purchase #2	$6.83	13.843%	$7.7755	$7.78	$7.80	$7.80
Purchase #3	$31.61	11.595%	$35.2752	$35.28	$35.30	$35.30
Purchase #4	$239.34	9.410%	$261.8619	$261.86	$261.85	$261.90
Purchase #5	$127.76	4.752%	$133.8312	$133.83	$133.85	$133.80
Purchase #6	$221.79	11.196%	$246.6216	$246.62	$246.60	$246.60
Purchase #7	$93.36	7.594%	$100.4498	$100.45	$100.45	$100.40
7 purchase totals =	$925.07		$1,007.8679	$1,007.87	$1,007.90	$1,007.90