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	$215.90	4.493%	$225.6004	$225.60	$225.60	$225.60
Purchase #2	$136.65	6.312%	$145.2753	$145.28	$145.30	$145.30
Purchase #3	$250.61	3.801%	$260.1357	$260.14	$260.15	$260.10
Purchase #4	$241.49	13.663%	$274.4848	$274.48	$274.50	$274.50
Purchase #5	$193.44	10.141%	$213.0568	$213.06	$213.05	$213.10
Purchase #6	$225.25	3.635%	$233.4378	$233.44	$233.45	$233.40
Purchase #7	$40.59	8.133%	$43.8912	$43.89	$43.90	$43.90
7 purchase totals =	$1,303.93		$1,395.8820	$1,395.89	$1,395.95	$1,395.90