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	$116.38	7.733%	$125.3797	$125.38	$125.40	$125.40
Purchase #2	$180.37	10.801%	$199.8518	$199.85	$199.85	$199.90
Purchase #3	$131.90	7.732%	$142.0985	$142.10	$142.10	$142.10
Purchase #4	$114.98	3.119%	$118.5662	$118.57	$118.55	$118.60
Purchase #5	$110.49	11.605%	$123.3124	$123.31	$123.30	$123.30
Purchase #6	$31.75	7.834%	$34.2373	$34.24	$34.25	$34.20
Purchase #7	$191.45	9.765%	$210.1451	$210.15	$210.15	$210.10
7 purchase totals =	$877.32		$953.5910	$953.60	$953.60	$953.60