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	$89.55	8.350%	$97.0274	$97.03	$97.05	$97.00
Purchase #2	$43.32	3.746%	$44.9428	$44.94	$44.95	$44.90
Purchase #3	$99.85	4.664%	$104.507	$104.51	$104.50	$104.50
Purchase #4	$108.65	13.809%	$123.6535	$123.65	$123.65	$123.70
Purchase #5	$24.86	13.715%	$28.2695	$28.27	$28.25	$28.30
Purchase #6	$198.66	6.299%	$211.1736	$211.17	$211.15	$211.20
Purchase #7	$137.58	9.464%	$150.6006	$150.60	$150.60	$150.60
7 purchase totals =	$702.47		$760.1744	$760.17	$760.15	$760.20