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	$110.61	6.185%	$117.4512	$117.45	$117.45	$117.50
Purchase #2	$205.94	13.315%	$233.3609	$233.36	$233.35	$233.40
Purchase #3	$11.92	7.810%	$12.851	$12.85	$12.85	$12.90
Purchase #4	$57.72	3.236%	$59.5878	$59.59	$59.60	$59.60
Purchase #5	$196.94	13.208%	$222.9518	$222.95	$222.95	$223.00
Purchase #6	$157.68	11.773%	$176.2437	$176.24	$176.25	$176.20
Purchase #7	$130.41	11.168%	$144.9742	$144.97	$144.95	$145.00
7 purchase totals =	$871.22		$967.4206	$967.41	$967.40	$967.60