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	$180.99	8.288%	$195.9905	$195.99	$196.00	$196.00
Purchase #2	$114.93	11.274%	$127.8872	$127.89	$127.90	$127.90
Purchase #3	$97.39	5.286%	$102.538	$102.54	$102.55	$102.50
Purchase #4	$140.27	9.353%	$153.3895	$153.39	$153.40	$153.40
Purchase #5	$245.86	9.430%	$269.0446	$269.04	$269.05	$269.00
Purchase #6	$66.52	7.493%	$71.5043	$71.50	$71.50	$71.50
Purchase #7	$140.31	10.375%	$154.8672	$154.87	$154.85	$154.90
7 purchase totals =	$986.27		$1,075.2213	$1,075.22	$1,075.25	$1,075.20