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	$179.35	9.312%	$196.0511	$196.05	$196.05	$196.10
Purchase #2	$27.52	8.518%	$29.8642	$29.86	$29.85	$29.90
Purchase #3	$76.87	9.482%	$84.1588	$84.16	$84.15	$84.20
Purchase #4	$185.64	3.818%	$192.7277	$192.73	$192.75	$192.70
Purchase #5	$10.69	10.196%	$11.78	$11.78	$11.80	$11.80
Purchase #6	$217.80	12.422%	$244.8551	$244.86	$244.85	$244.90
Purchase #7	$96.31	7.859%	$103.879	$103.88	$103.90	$103.90
7 purchase totals =	$794.18		$863.3159	$863.32	$863.35	$863.50