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	$184.49	4.255%	$192.34	$192.34	$192.35	$192.30
Purchase #2	$32.76	3.268%	$33.8306	$33.83	$33.85	$33.80
Purchase #3	$10.44	6.562%	$11.1251	$11.13	$11.15	$11.10
Purchase #4	$18.42	12.234%	$20.6735	$20.67	$20.65	$20.70
Purchase #5	$18.27	6.585%	$19.4731	$19.47	$19.45	$19.50
Purchase #6	$18.79	11.179%	$20.8905	$20.89	$20.90	$20.90
Purchase #7	$112.35	4.183%	$117.0496	$117.05	$117.05	$117.00
7 purchase totals =	$395.52		$415.3824	$415.38	$415.40	$415.30