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	$84.89	10.638%	$93.9206	$93.92	$93.90	$93.90
Purchase #2	$147.54	13.850%	$167.9743	$167.97	$167.95	$168.00
Purchase #3	$158.46	6.341%	$168.5079	$168.51	$168.50	$168.50
Purchase #4	$49.96	9.684%	$54.7981	$54.80	$54.80	$54.80
Purchase #5	$127.67	11.868%	$142.8219	$142.82	$142.80	$142.80
Purchase #6	$172.35	3.820%	$178.9338	$178.93	$178.95	$178.90
Purchase #7	$221.45	9.446%	$242.3682	$242.37	$242.35	$242.40
7 purchase totals =	$962.32		$1,049.3248	$1,049.32	$1,049.25	$1,049.30