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	$187.41	9.413%	$205.0509	$205.05	$205.05	$205.10
Purchase #2	$56.85	11.238%	$63.2388	$63.24	$63.25	$63.20
Purchase #3	$97.43	3.194%	$100.5419	$100.54	$100.55	$100.50
Purchase #4	$137.91	10.247%	$152.0416	$152.04	$152.05	$152.00
Purchase #5	$249.87	11.324%	$278.1653	$278.17	$278.15	$278.20
Purchase #6	$25.83	6.414%	$27.4867	$27.49	$27.50	$27.50
Purchase #7	$161.67	11.353%	$180.0244	$180.02	$180.00	$180.00
7 purchase totals =	$916.97		$1,006.5496	$1,006.55	$1,006.55	$1,006.50