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	$90.72	3.771%	$94.1411	$94.14	$94.15	$94.10
Purchase #2	$207.94	12.277%	$233.4688	$233.47	$233.45	$233.50
Purchase #3	$153.86	4.705%	$161.0991	$161.10	$161.10	$161.10
Purchase #4	$116.70	6.695%	$124.5131	$124.51	$124.50	$124.50
Purchase #5	$72.77	5.842%	$77.0212	$77.02	$77.00	$77.00
Purchase #6	$162.64	3.841%	$168.887	$168.89	$168.90	$168.90
Purchase #7	$192.79	8.653%	$209.4721	$209.47	$209.45	$209.50
7 purchase totals =	$997.42		$1,068.6024	$1,068.60	$1,068.55	$1,068.60