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	$190.59	7.472%	$204.8309	$204.83	$204.85	$204.80
Purchase #2	$209.89	6.255%	$223.0186	$223.02	$223.00	$223.00
Purchase #3	$222.41	11.541%	$248.0783	$248.08	$248.10	$248.10
Purchase #4	$138.67	3.739%	$143.8549	$143.85	$143.85	$143.90
Purchase #5	$74.50	4.763%	$78.0484	$78.05	$78.05	$78.00
Purchase #6	$128.92	13.781%	$146.6865	$146.69	$146.70	$146.70
Purchase #7	$71.30	3.356%	$73.6928	$73.69	$73.70	$73.70
7 purchase totals =	$1,036.28		$1,118.2104	$1,118.21	$1,118.25	$1,118.20