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	$145.67	3.873%	$151.3118	$151.31	$151.30	$151.30
Purchase #2	$210.49	4.389%	$219.7284	$219.73	$219.75	$219.70
Purchase #3	$234.82	11.701%	$262.2963	$262.30	$262.30	$262.30
Purchase #4	$54.86	4.366%	$57.2552	$57.26	$57.25	$57.30
Purchase #5	$83.50	13.346%	$94.6439	$94.64	$94.65	$94.60
Purchase #6	$164.81	11.173%	$183.2242	$183.22	$183.20	$183.20
Purchase #7	$128.53	11.587%	$143.4228	$143.42	$143.40	$143.40
7 purchase totals =	$1,022.68		$1,111.8826	$1,111.88	$1,111.85	$1,111.80