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	$161.58	4.856%	$169.4263	$169.43	$169.45	$169.40
Purchase #2	$242.48	8.366%	$262.7659	$262.77	$262.75	$262.80
Purchase #3	$191.82	7.156%	$205.5466	$205.55	$205.55	$205.50
Purchase #4	$30.27	8.413%	$32.8166	$32.82	$32.80	$32.80
Purchase #5	$30.87	13.752%	$35.1152	$35.12	$35.10	$35.10
Purchase #6	$89.41	6.712%	$95.4112	$95.41	$95.40	$95.40
Purchase #7	$195.65	11.397%	$217.9482	$217.95	$217.95	$217.90
7 purchase totals =	$942.08		$1,019.0300	$1,019.05	$1,019.00	$1,018.90