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	$214.92	10.700%	$237.9164	$237.92	$237.90	$237.90
Purchase #2	$19.45	5.283%	$20.4775	$20.48	$20.50	$20.50
Purchase #3	$199.40	7.774%	$214.9014	$214.90	$214.90	$214.90
Purchase #4	$181.36	10.749%	$200.8544	$200.85	$200.85	$200.90
Purchase #5	$86.85	7.612%	$93.461	$93.46	$93.45	$93.50
Purchase #6	$9.66	12.113%	$10.8301	$10.83	$10.85	$10.80
Purchase #7	$157.69	4.153%	$164.2389	$164.24	$164.25	$164.20
7 purchase totals =	$869.33		$942.6797	$942.68	$942.70	$942.70