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	$58.77	7.345%	$63.0867	$63.09	$63.10	$63.10
Purchase #2	$93.72	4.824%	$98.2411	$98.24	$98.25	$98.20
Purchase #3	$163.55	5.405%	$172.3899	$172.39	$172.40	$172.40
Purchase #4	$250.48	3.606%	$259.5123	$259.51	$259.50	$259.50
Purchase #5	$168.49	9.841%	$185.0711	$185.07	$185.05	$185.10
Purchase #6	$123.61	5.195%	$130.0315	$130.03	$130.05	$130.00
Purchase #7	$114.66	7.504%	$123.2641	$123.26	$123.25	$123.30
7 purchase totals =	$973.28		$1,031.5967	$1,031.59	$1,031.60	$1,031.60