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	$211.45	7.746%	$227.8289	$227.83	$227.85	$227.80
Purchase #2	$25.94	6.223%	$27.5542	$27.55	$27.55	$27.60
Purchase #3	$92.56	11.230%	$102.9545	$102.95	$102.95	$103.00
Purchase #4	$128.90	8.310%	$139.6116	$139.61	$139.60	$139.60
Purchase #5	$135.63	12.147%	$152.105	$152.11	$152.10	$152.10
Purchase #6	$46.42	10.868%	$51.4649	$51.46	$51.45	$51.50
Purchase #7	$158.31	5.462%	$166.9569	$166.96	$166.95	$167.00
7 purchase totals =	$799.21		$868.4760	$868.47	$868.45	$868.60