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	$57.35	9.312%	$62.6904	$62.69	$62.70	$62.70
Purchase #2	$77.70	6.243%	$82.5508	$82.55	$82.55	$82.60
Purchase #3	$42.54	7.613%	$45.7786	$45.78	$45.80	$45.80
Purchase #4	$82.93	7.688%	$89.3057	$89.31	$89.30	$89.30
Purchase #5	$164.73	11.239%	$183.244	$183.24	$183.25	$183.20
Purchase #6	$34.88	8.638%	$37.8929	$37.89	$37.90	$37.90
Purchase #7	$91.52	12.201%	$102.6864	$102.69	$102.70	$102.70
7 purchase totals =	$551.65		$604.1488	$604.15	$604.20	$604.20