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	$55.48	11.707%	$61.975	$61.98	$62.00	$62.00
Purchase #2	$29.87	6.722%	$31.8779	$31.88	$31.90	$31.90
Purchase #3	$101.51	12.533%	$114.2322	$114.23	$114.25	$114.20
Purchase #4	$200.53	9.656%	$219.8932	$219.89	$219.90	$219.90
Purchase #5	$195.92	4.722%	$205.1713	$205.17	$205.15	$205.20
Purchase #6	$206.27	10.848%	$228.6462	$228.65	$228.65	$228.60
Purchase #7	$85.43	13.181%	$96.6905	$96.69	$96.70	$96.70
7 purchase totals =	$875.01		$958.4863	$958.49	$958.55	$958.50