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	$116.72	7.575%	$125.5615	$125.56	$125.55	$125.60
Purchase #2	$102.60	5.583%	$108.3282	$108.33	$108.35	$108.30
Purchase #3	$133.68	8.707%	$145.3195	$145.32	$145.30	$145.30
Purchase #4	$126.96	12.499%	$142.8287	$142.83	$142.85	$142.80
Purchase #5	$93.48	11.133%	$103.8871	$103.89	$103.90	$103.90
Purchase #6	$29.43	13.165%	$33.3045	$33.30	$33.30	$33.30
Purchase #7	$92.44	11.737%	$103.2897	$103.29	$103.30	$103.30
7 purchase totals =	$695.31		$762.5192	$762.52	$762.55	$762.50