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	$196.86	12.596%	$221.6565	$221.66	$221.65	$221.70
Purchase #2	$160.95	4.138%	$167.6101	$167.61	$167.60	$167.60
Purchase #3	$59.85	6.569%	$63.7815	$63.78	$63.80	$63.80
Purchase #4	$176.43	11.357%	$196.4672	$196.47	$196.45	$196.50
Purchase #5	$25.37	13.510%	$28.7975	$28.80	$28.80	$28.80
Purchase #6	$200.94	4.782%	$210.549	$210.55	$210.55	$210.50
Purchase #7	$218.61	6.574%	$232.9814	$232.98	$233.00	$233.00
7 purchase totals =	$1,039.01		$1,121.8432	$1,121.85	$1,121.85	$1,121.90