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	$61.50	4.211%	$64.0898	$64.09	$64.10	$64.10
Purchase #2	$97.66	13.773%	$111.1107	$111.11	$111.10	$111.10
Purchase #3	$15.96	13.711%	$18.1483	$18.15	$18.15	$18.10
Purchase #4	$83.96	10.598%	$92.8581	$92.86	$92.85	$92.90
Purchase #5	$57.90	5.278%	$60.956	$60.96	$60.95	$61.00
Purchase #6	$185.98	13.442%	$210.9794	$210.98	$211.00	$211.00
Purchase #7	$189.95	4.585%	$198.6592	$198.66	$198.65	$198.70
7 purchase totals =	$692.91		$756.8015	$756.81	$756.80	$756.90