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	$244.72	7.247%	$262.4549	$262.45	$262.45	$262.50
Purchase #2	$219.96	9.676%	$241.2433	$241.24	$241.25	$241.20
Purchase #3	$40.82	3.679%	$42.3218	$42.32	$42.30	$42.30
Purchase #4	$184.93	6.310%	$196.5991	$196.60	$196.60	$196.60
Purchase #5	$239.95	13.667%	$272.744	$272.74	$272.75	$272.70
Purchase #6	$44.99	13.682%	$51.1455	$51.15	$51.15	$51.10
Purchase #7	$168.39	8.153%	$182.1188	$182.12	$182.10	$182.10
7 purchase totals =	$1,143.76		$1,248.6274	$1,248.62	$1,248.60	$1,248.50