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	$116.83	13.141%	$132.1826	$132.18	$132.20	$132.20
Purchase #2	$173.38	8.851%	$188.7259	$188.73	$188.75	$188.70
Purchase #3	$248.73	10.175%	$274.0383	$274.04	$274.05	$274.00
Purchase #4	$52.52	10.278%	$57.918	$57.92	$57.90	$57.90
Purchase #5	$123.28	10.631%	$136.3859	$136.39	$136.40	$136.40
Purchase #6	$111.74	4.431%	$116.6912	$116.69	$116.70	$116.70
Purchase #7	$102.91	13.322%	$116.6197	$116.62	$116.60	$116.60
7 purchase totals =	$929.39		$1,022.5616	$1,022.57	$1,022.60	$1,022.50