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	$194.60	4.453%	$203.2655	$203.27	$203.25	$203.30
Purchase #2	$29.56	12.124%	$33.1439	$33.14	$33.15	$33.10
Purchase #3	$21.51	11.130%	$23.9041	$23.90	$23.90	$23.90
Purchase #4	$88.72	6.334%	$94.3395	$94.34	$94.35	$94.30
Purchase #5	$246.82	3.455%	$255.3476	$255.35	$255.35	$255.30
Purchase #6	$19.89	8.288%	$21.5385	$21.54	$21.55	$21.50
Purchase #7	$41.66	4.366%	$43.4789	$43.48	$43.50	$43.50
7 purchase totals =	$642.76		$675.0180	$675.02	$675.05	$674.90