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	$194.41	10.685%	$215.1827	$215.18	$215.20	$215.20
Purchase #2	$118.77	5.401%	$125.1848	$125.18	$125.20	$125.20
Purchase #3	$212.84	9.855%	$233.8154	$233.82	$233.80	$233.80
Purchase #4	$10.48	8.335%	$11.3535	$11.35	$11.35	$11.40
Purchase #5	$72.95	13.208%	$82.5852	$82.59	$82.60	$82.60
Purchase #6	$176.60	11.147%	$196.2856	$196.29	$196.30	$196.30
Purchase #7	$217.50	10.145%	$239.5654	$239.57	$239.55	$239.60
7 purchase totals =	$1,003.55		$1,103.9726	$1,103.98	$1,104.00	$1,104.10