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	$179.31	8.657%	$194.8329	$194.83	$194.85	$194.80
Purchase #2	$30.37	9.705%	$33.3174	$33.32	$33.30	$33.30
Purchase #3	$176.30	7.359%	$189.2739	$189.27	$189.25	$189.30
Purchase #4	$214.48	4.232%	$223.5568	$223.56	$223.55	$223.60
Purchase #5	$232.88	9.752%	$255.5905	$255.59	$255.60	$255.60
Purchase #6	$59.86	9.163%	$65.345	$65.35	$65.35	$65.30
Purchase #7	$72.47	12.377%	$81.4396	$81.44	$81.45	$81.40
7 purchase totals =	$965.67		$1,043.3561	$1,043.36	$1,043.35	$1,043.30