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	$85.62	9.743%	$93.962	$93.96	$93.95	$94.00
Purchase #2	$68.37	13.226%	$77.4126	$77.41	$77.40	$77.40
Purchase #3	$89.50	12.270%	$100.4817	$100.48	$100.50	$100.50
Purchase #4	$168.43	10.176%	$185.5694	$185.57	$185.55	$185.60
Purchase #5	$69.96	3.309%	$72.275	$72.28	$72.30	$72.30
Purchase #6	$146.72	5.640%	$154.995	$155.00	$155.00	$155.00
Purchase #7	$66.70	6.493%	$71.0308	$71.03	$71.05	$71.00
7 purchase totals =	$695.30		$755.7265	$755.73	$755.75	$755.80