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	$184.58	12.679%	$207.9829	$207.98	$208.00	$208.00
Purchase #2	$189.85	8.138%	$205.3	$205.30	$205.30	$205.30
Purchase #3	$35.43	6.127%	$37.6008	$37.60	$37.60	$37.60
Purchase #4	$250.38	3.541%	$259.246	$259.25	$259.25	$259.20
Purchase #5	$40.94	5.757%	$43.2969	$43.30	$43.30	$43.30
Purchase #6	$78.70	4.686%	$82.3879	$82.39	$82.40	$82.40
Purchase #7	$227.89	11.321%	$253.6894	$253.69	$253.70	$253.70
7 purchase totals =	$1,007.77		$1,089.5039	$1,089.51	$1,089.55	$1,089.50