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	$55.54	12.652%	$62.5669	$62.57	$62.55	$62.60
Purchase #2	$88.51	10.721%	$97.9992	$98.00	$98.00	$98.00
Purchase #3	$250.48	3.312%	$258.7759	$258.78	$258.80	$258.80
Purchase #4	$99.75	3.862%	$103.6023	$103.60	$103.60	$103.60
Purchase #5	$159.96	13.648%	$181.7913	$181.79	$181.80	$181.80
Purchase #6	$169.66	10.338%	$187.1995	$187.20	$187.20	$187.20
Purchase #7	$137.50	6.527%	$146.4746	$146.47	$146.45	$146.50
7 purchase totals =	$961.40		$1,038.4097	$1,038.41	$1,038.40	$1,038.50