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	$36.94	11.194%	$41.0751	$41.08	$41.10	$41.10
Purchase #2	$145.32	6.426%	$154.6583	$154.66	$154.65	$154.70
Purchase #3	$183.90	7.860%	$198.3545	$198.35	$198.35	$198.40
Purchase #4	$181.63	5.125%	$190.9385	$190.94	$190.95	$190.90
Purchase #5	$215.98	5.867%	$228.6515	$228.65	$228.65	$228.70
Purchase #6	$174.96	8.684%	$190.1535	$190.15	$190.15	$190.20
Purchase #7	$172.41	11.816%	$192.782	$192.78	$192.80	$192.80
7 purchase totals =	$1,111.14		$1,196.6134	$1,196.61	$1,196.65	$1,196.80