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	$167.73	7.569%	$180.4255	$180.43	$180.45	$180.40
Purchase #2	$226.70	6.491%	$241.4151	$241.42	$241.40	$241.40
Purchase #3	$98.87	6.745%	$105.5388	$105.54	$105.55	$105.50
Purchase #4	$81.89	11.675%	$91.4507	$91.45	$91.45	$91.50
Purchase #5	$191.83	3.153%	$197.8784	$197.88	$197.90	$197.90
Purchase #6	$248.96	4.677%	$260.6039	$260.60	$260.60	$260.60
Purchase #7	$243.54	5.389%	$256.6644	$256.66	$256.65	$256.70
7 purchase totals =	$1,259.52		$1,333.9768	$1,333.98	$1,334.00	$1,334.00