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	$142.42	7.372%	$152.9192	$152.92	$152.90	$152.90
Purchase #2	$101.94	7.663%	$109.7517	$109.75	$109.75	$109.80
Purchase #3	$196.43	9.391%	$214.8767	$214.88	$214.90	$214.90
Purchase #4	$159.25	11.754%	$177.9682	$177.97	$177.95	$178.00
Purchase #5	$69.40	12.679%	$78.1992	$78.20	$78.20	$78.20
Purchase #6	$189.72	8.371%	$205.6015	$205.60	$205.60	$205.60
Purchase #7	$138.66	9.638%	$152.0241	$152.02	$152.00	$152.00
7 purchase totals =	$997.82		$1,091.3406	$1,091.34	$1,091.30	$1,091.40