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	$197.68	10.246%	$217.9343	$217.93	$217.95	$217.90
Purchase #2	$84.98	5.688%	$89.8137	$89.81	$89.80	$89.80
Purchase #3	$126.73	12.526%	$142.6042	$142.60	$142.60	$142.60
Purchase #4	$175.97	11.809%	$196.7503	$196.75	$196.75	$196.80
Purchase #5	$219.38	4.612%	$229.4978	$229.50	$229.50	$229.50
Purchase #6	$205.31	10.851%	$227.5882	$227.59	$227.60	$227.60
Purchase #7	$44.70	3.140%	$46.1036	$46.10	$46.10	$46.10
7 purchase totals =	$1,054.75		$1,150.2921	$1,150.28	$1,150.30	$1,150.30