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	$194.35	10.761%	$215.264	$215.26	$215.25	$215.30
Purchase #2	$41.98	11.667%	$46.8778	$46.88	$46.90	$46.90
Purchase #3	$204.68	12.852%	$230.9855	$230.99	$231.00	$231.00
Purchase #4	$190.96	10.277%	$210.585	$210.59	$210.60	$210.60
Purchase #5	$196.38	10.209%	$216.4284	$216.43	$216.45	$216.40
Purchase #6	$220.38	9.598%	$241.5321	$241.53	$241.55	$241.50
Purchase #7	$58.25	5.670%	$61.5528	$61.55	$61.55	$61.60
7 purchase totals =	$1,106.98		$1,223.2256	$1,223.23	$1,223.30	$1,223.30