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	$246.93	6.312%	$262.5162	$262.52	$262.50	$262.50
Purchase #2	$63.51	13.421%	$72.0337	$72.03	$72.05	$72.00
Purchase #3	$24.69	7.208%	$26.4697	$26.47	$26.45	$26.50
Purchase #4	$19.83	13.327%	$22.4727	$22.47	$22.45	$22.50
Purchase #5	$114.72	4.867%	$120.3034	$120.30	$120.30	$120.30
Purchase #6	$206.47	3.292%	$213.267	$213.27	$213.25	$213.30
Purchase #7	$124.78	5.300%	$131.3933	$131.39	$131.40	$131.40
7 purchase totals =	$800.93		$848.4560	$848.45	$848.40	$848.50