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	$224.68	7.568%	$241.6838	$241.68	$241.70	$241.70
Purchase #2	$96.55	6.811%	$103.126	$103.13	$103.15	$103.10
Purchase #3	$52.40	13.319%	$59.3792	$59.38	$59.40	$59.40
Purchase #4	$12.49	3.571%	$12.936	$12.94	$12.95	$12.90
Purchase #5	$247.70	9.365%	$270.8971	$270.90	$270.90	$270.90
Purchase #6	$110.68	5.224%	$116.4619	$116.46	$116.45	$116.50
Purchase #7	$224.81	11.431%	$250.508	$250.51	$250.50	$250.50
7 purchase totals =	$969.31		$1,054.9920	$1,055.00	$1,055.05	$1,055.00