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	$74.59	11.222%	$82.9605	$82.96	$82.95	$83.00
Purchase #2	$32.35	6.668%	$34.5071	$34.51	$34.50	$34.50
Purchase #3	$50.55	6.362%	$53.766	$53.77	$53.75	$53.80
Purchase #4	$184.32	11.422%	$205.373	$205.37	$205.35	$205.40
Purchase #5	$20.76	3.227%	$21.4299	$21.43	$21.45	$21.40
Purchase #6	$82.50	3.371%	$85.2811	$85.28	$85.30	$85.30
Purchase #7	$134.69	6.526%	$143.4799	$143.48	$143.50	$143.50
7 purchase totals =	$579.76		$626.7975	$626.80	$626.80	$626.90