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	$195.95	13.205%	$221.8252	$221.83	$221.85	$221.80
Purchase #2	$189.26	8.547%	$205.4361	$205.44	$205.45	$205.40
Purchase #3	$57.89	4.326%	$60.3943	$60.39	$60.40	$60.40
Purchase #4	$44.83	7.208%	$48.0613	$48.06	$48.05	$48.10
Purchase #5	$250.67	12.114%	$281.0362	$281.04	$281.05	$281.00
Purchase #6	$121.26	5.187%	$127.5498	$127.55	$127.55	$127.50
Purchase #7	$213.69	4.595%	$223.5091	$223.51	$223.50	$223.50
7 purchase totals =	$1,073.55		$1,167.8120	$1,167.82	$1,167.85	$1,167.70