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	$87.57	10.512%	$96.7754	$96.78	$96.80	$96.80
Purchase #2	$42.56	4.472%	$44.4633	$44.46	$44.45	$44.50
Purchase #3	$219.67	11.518%	$244.9716	$244.97	$244.95	$245.00
Purchase #4	$171.88	7.133%	$184.1402	$184.14	$184.15	$184.10
Purchase #5	$240.26	6.585%	$256.0811	$256.08	$256.10	$256.10
Purchase #6	$94.45	6.523%	$100.611	$100.61	$100.60	$100.60
Purchase #7	$102.59	6.103%	$108.8511	$108.85	$108.85	$108.90
7 purchase totals =	$958.98		$1,035.8937	$1,035.89	$1,035.90	$1,036.00