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	$86.40	10.682%	$95.6292	$95.63	$95.65	$95.60
Purchase #2	$199.80	11.336%	$222.4493	$222.45	$222.45	$222.40
Purchase #3	$127.98	12.158%	$143.5398	$143.54	$143.55	$143.50
Purchase #4	$40.96	7.813%	$44.1602	$44.16	$44.15	$44.20
Purchase #5	$115.91	7.863%	$125.024	$125.02	$125.00	$125.00
Purchase #6	$79.84	6.725%	$85.2092	$85.21	$85.20	$85.20
Purchase #7	$64.81	10.267%	$71.464	$71.46	$71.45	$71.50
7 purchase totals =	$715.70		$787.4757	$787.47	$787.45	$787.40