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	$216.49	6.527%	$230.6203	$230.62	$230.60	$230.60
Purchase #2	$12.82	7.581%	$13.7919	$13.79	$13.80	$13.80
Purchase #3	$135.52	6.330%	$144.0984	$144.10	$144.10	$144.10
Purchase #4	$199.63	5.608%	$210.8253	$210.83	$210.85	$210.80
Purchase #5	$233.57	12.557%	$262.8994	$262.90	$262.90	$262.90
Purchase #6	$71.89	9.361%	$78.6196	$78.62	$78.60	$78.60
Purchase #7	$190.83	13.337%	$216.281	$216.28	$216.30	$216.30
7 purchase totals =	$1,060.75		$1,157.1359	$1,157.14	$1,157.15	$1,157.10