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	$214.51	12.469%	$241.2573	$241.26	$241.25	$241.30
Purchase #2	$76.34	5.218%	$80.3234	$80.32	$80.30	$80.30
Purchase #3	$6.48	4.614%	$6.779	$6.78	$6.80	$6.80
Purchase #4	$203.86	9.809%	$223.8566	$223.86	$223.85	$223.90
Purchase #5	$198.64	3.523%	$205.6381	$205.64	$205.65	$205.60
Purchase #6	$97.46	5.316%	$102.641	$102.64	$102.65	$102.60
Purchase #7	$145.76	11.382%	$162.3504	$162.35	$162.35	$162.40
7 purchase totals =	$943.05		$1,022.8458	$1,022.85	$1,022.85	$1,022.90