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	$32.30	9.518%	$35.3743	$35.37	$35.35	$35.40
Purchase #2	$85.59	5.469%	$90.2709	$90.27	$90.25	$90.30
Purchase #3	$73.40	4.207%	$76.4879	$76.49	$76.50	$76.50
Purchase #4	$86.90	8.249%	$94.0684	$94.07	$94.05	$94.10
Purchase #5	$44.98	4.513%	$47.0099	$47.01	$47.00	$47.00
Purchase #6	$109.37	6.368%	$116.3347	$116.33	$116.35	$116.30
Purchase #7	$219.89	12.219%	$246.7584	$246.76	$246.75	$246.80
7 purchase totals =	$652.43		$706.3045	$706.30	$706.25	$706.40