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	$176.88	10.404%	$195.2826	$195.28	$195.30	$195.30
Purchase #2	$110.26	3.779%	$114.4267	$114.43	$114.45	$114.40
Purchase #3	$122.31	3.866%	$127.0385	$127.04	$127.05	$127.00
Purchase #4	$202.77	6.460%	$215.8689	$215.87	$215.85	$215.90
Purchase #5	$44.86	4.198%	$46.7432	$46.74	$46.75	$46.70
Purchase #6	$239.61	6.696%	$255.6543	$255.65	$255.65	$255.70
Purchase #7	$124.71	5.518%	$131.5915	$131.59	$131.60	$131.60
7 purchase totals =	$1,021.40		$1,086.6057	$1,086.60	$1,086.65	$1,086.60