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	$161.77	10.320%	$178.4647	$178.46	$178.45	$178.50
Purchase #2	$13.32	9.676%	$14.6088	$14.61	$14.60	$14.60
Purchase #3	$205.59	13.765%	$233.8895	$233.89	$233.90	$233.90
Purchase #4	$83.86	11.567%	$93.5601	$93.56	$93.55	$93.60
Purchase #5	$78.76	4.740%	$82.4932	$82.49	$82.50	$82.50
Purchase #6	$162.84	8.387%	$176.4974	$176.50	$176.50	$176.50
Purchase #7	$65.54	3.508%	$67.8391	$67.84	$67.85	$67.80
7 purchase totals =	$771.68		$847.3528	$847.35	$847.35	$847.40