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	$107.57	3.754%	$111.6082	$111.61	$111.60	$111.60
Purchase #2	$139.63	4.237%	$145.5461	$145.55	$145.55	$145.50
Purchase #3	$197.74	11.604%	$220.6857	$220.69	$220.70	$220.70
Purchase #4	$114.44	11.792%	$127.9348	$127.93	$127.95	$127.90
Purchase #5	$236.83	10.166%	$260.9061	$260.91	$260.90	$260.90
Purchase #6	$118.32	6.321%	$125.799	$125.80	$125.80	$125.80
Purchase #7	$152.62	11.124%	$169.5974	$169.60	$169.60	$169.60
7 purchase totals =	$1,067.15		$1,162.0773	$1,162.09	$1,162.10	$1,162.00