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	$210.60	7.294%	$225.9612	$225.96	$225.95	$226.00
Purchase #2	$206.49	7.202%	$221.3614	$221.36	$221.35	$221.40
Purchase #3	$111.74	6.820%	$119.3607	$119.36	$119.35	$119.40
Purchase #4	$41.82	9.747%	$45.8962	$45.90	$45.90	$45.90
Purchase #5	$139.96	12.556%	$157.5334	$157.53	$157.55	$157.50
Purchase #6	$151.45	7.347%	$162.577	$162.58	$162.60	$162.60
Purchase #7	$108.53	13.853%	$123.5647	$123.56	$123.55	$123.60
7 purchase totals =	$970.59		$1,056.2546	$1,056.25	$1,056.25	$1,056.40