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	$201.48	9.108%	$219.8308	$219.83	$219.85	$219.80
Purchase #2	$115.60	7.748%	$124.5567	$124.56	$124.55	$124.60
Purchase #3	$184.60	6.227%	$196.095	$196.10	$196.10	$196.10
Purchase #4	$222.40	8.424%	$241.135	$241.14	$241.15	$241.10
Purchase #5	$111.77	13.271%	$126.603	$126.60	$126.60	$126.60
Purchase #6	$58.97	4.254%	$61.4786	$61.48	$61.50	$61.50
Purchase #7	$83.54	13.412%	$94.7444	$94.74	$94.75	$94.70
7 purchase totals =	$978.36		$1,064.4435	$1,064.45	$1,064.50	$1,064.40