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	$86.27	7.420%	$92.6712	$92.67	$92.65	$92.70
Purchase #2	$115.73	10.168%	$127.4974	$127.50	$127.50	$127.50
Purchase #3	$227.79	10.773%	$252.3298	$252.33	$252.35	$252.30
Purchase #4	$192.72	10.726%	$213.3911	$213.39	$213.40	$213.40
Purchase #5	$45.46	4.262%	$47.3975	$47.40	$47.40	$47.40
Purchase #6	$87.96	13.305%	$99.6631	$99.66	$99.65	$99.70
Purchase #7	$56.77	11.861%	$63.5035	$63.50	$63.50	$63.50
7 purchase totals =	$812.70		$896.4536	$896.45	$896.45	$896.50