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	$134.96	4.485%	$141.013	$141.01	$141.00	$141.00
Purchase #2	$51.84	5.647%	$54.7674	$54.77	$54.75	$54.80
Purchase #3	$67.45	13.307%	$76.4256	$76.43	$76.45	$76.40
Purchase #4	$105.98	5.353%	$111.6531	$111.65	$111.65	$111.70
Purchase #5	$185.86	11.492%	$207.219	$207.22	$207.20	$207.20
Purchase #6	$191.52	12.430%	$215.3259	$215.33	$215.35	$215.30
Purchase #7	$177.50	5.621%	$187.4773	$187.48	$187.50	$187.50
7 purchase totals =	$915.11		$993.8813	$993.89	$993.90	$993.90