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	$151.54	7.542%	$162.9691	$162.97	$162.95	$163.00
Purchase #2	$18.48	10.209%	$20.3666	$20.37	$20.35	$20.40
Purchase #3	$133.35	6.538%	$142.0684	$142.07	$142.05	$142.10
Purchase #4	$95.27	8.366%	$103.2403	$103.24	$103.25	$103.20
Purchase #5	$142.56	11.690%	$159.2253	$159.23	$159.25	$159.20
Purchase #6	$196.68	9.572%	$215.5062	$215.51	$215.50	$215.50
Purchase #7	$233.58	8.686%	$253.8688	$253.87	$253.85	$253.90
7 purchase totals =	$971.46		$1,057.2447	$1,057.26	$1,057.20	$1,057.30