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	$43.92	7.737%	$47.3181	$47.32	$47.30	$47.30
Purchase #2	$182.52	7.720%	$196.6105	$196.61	$196.60	$196.60
Purchase #3	$126.98	3.230%	$131.0815	$131.08	$131.10	$131.10
Purchase #4	$242.87	5.282%	$255.6984	$255.70	$255.70	$255.70
Purchase #5	$159.69	5.721%	$168.8259	$168.83	$168.85	$168.80
Purchase #6	$85.43	8.619%	$92.7932	$92.79	$92.80	$92.80
Purchase #7	$157.45	6.511%	$167.7016	$167.70	$167.70	$167.70
7 purchase totals =	$998.86		$1,060.0292	$1,060.03	$1,060.05	$1,060.00