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	$149.26	3.218%	$154.0632	$154.06	$154.05	$154.10
Purchase #2	$181.65	4.535%	$189.8878	$189.89	$189.90	$189.90
Purchase #3	$97.35	6.832%	$104.001	$104.00	$104.00	$104.00
Purchase #4	$56.87	11.299%	$63.2957	$63.30	$63.30	$63.30
Purchase #5	$200.52	6.647%	$213.8486	$213.85	$213.85	$213.80
Purchase #6	$121.42	4.592%	$126.9956	$127.00	$127.00	$127.00
Purchase #7	$182.53	7.617%	$196.4333	$196.43	$196.45	$196.40
7 purchase totals =	$989.60		$1,048.5252	$1,048.53	$1,048.55	$1,048.50