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	$59.43	5.576%	$62.7438	$62.74	$62.75	$62.70
Purchase #2	$53.25	4.815%	$55.814	$55.81	$55.80	$55.80
Purchase #3	$207.81	4.483%	$217.1261	$217.13	$217.15	$217.10
Purchase #4	$80.81	10.478%	$89.2773	$89.28	$89.30	$89.30
Purchase #5	$92.66	7.308%	$99.4316	$99.43	$99.45	$99.40
Purchase #6	$90.38	6.525%	$96.2773	$96.28	$96.30	$96.30
Purchase #7	$103.40	12.445%	$116.2681	$116.27	$116.25	$116.30
7 purchase totals =	$687.74		$736.9382	$736.94	$737.00	$736.90