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	$67.25	13.107%	$76.0645	$76.06	$76.05	$76.10
Purchase #2	$52.89	3.789%	$54.894	$54.89	$54.90	$54.90
Purchase #3	$66.48	3.749%	$68.9723	$68.97	$68.95	$69.00
Purchase #4	$208.77	11.734%	$233.2671	$233.27	$233.25	$233.30
Purchase #5	$248.37	12.549%	$279.538	$279.54	$279.55	$279.50
Purchase #6	$155.77	4.210%	$162.3279	$162.33	$162.35	$162.30
Purchase #7	$222.82	3.256%	$230.075	$230.08	$230.10	$230.10
7 purchase totals =	$1,022.35		$1,105.1388	$1,105.14	$1,105.15	$1,105.20