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	$86.44	3.826%	$89.7472	$89.75	$89.75	$89.70
Purchase #2	$69.66	3.684%	$72.2263	$72.23	$72.25	$72.20
Purchase #3	$188.63	3.564%	$195.3528	$195.35	$195.35	$195.40
Purchase #4	$167.78	10.621%	$185.5999	$185.60	$185.60	$185.60
Purchase #5	$140.42	11.705%	$156.8562	$156.86	$156.85	$156.90
Purchase #6	$106.90	11.558%	$119.2555	$119.26	$119.25	$119.30
Purchase #7	$106.70	7.205%	$114.3877	$114.39	$114.40	$114.40
7 purchase totals =	$866.53		$933.4256	$933.44	$933.45	$933.50