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	$187.30	7.133%	$200.6601	$200.66	$200.65	$200.70
Purchase #2	$160.72	6.698%	$171.485	$171.49	$171.50	$171.50
Purchase #3	$25.48	10.258%	$28.0937	$28.09	$28.10	$28.10
Purchase #4	$26.96	3.232%	$27.8313	$27.83	$27.85	$27.80
Purchase #5	$56.30	9.179%	$61.4678	$61.47	$61.45	$61.50
Purchase #6	$71.27	7.296%	$76.4699	$76.47	$76.45	$76.50
Purchase #7	$84.45	3.457%	$87.3694	$87.37	$87.35	$87.40
7 purchase totals =	$612.48		$653.3772	$653.38	$653.35	$653.50