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	$237.61	9.866%	$261.0526	$261.05	$261.05	$261.10
Purchase #2	$168.91	12.704%	$190.3683	$190.37	$190.35	$190.40
Purchase #3	$127.33	11.658%	$142.1741	$142.17	$142.15	$142.20
Purchase #4	$222.45	11.270%	$247.5201	$247.52	$247.50	$247.50
Purchase #5	$15.48	3.551%	$16.0297	$16.03	$16.05	$16.00
Purchase #6	$72.50	5.704%	$76.6354	$76.64	$76.65	$76.60
Purchase #7	$121.57	8.168%	$131.4998	$131.50	$131.50	$131.50
7 purchase totals =	$965.85		$1,065.2800	$1,065.28	$1,065.25	$1,065.30