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	$162.60	11.120%	$180.6811	$180.68	$180.70	$180.70
Purchase #2	$89.98	11.778%	$100.5778	$100.58	$100.60	$100.60
Purchase #3	$148.76	9.140%	$162.3567	$162.36	$162.35	$162.40
Purchase #4	$13.58	5.299%	$14.2996	$14.30	$14.30	$14.30
Purchase #5	$215.84	8.451%	$234.0806	$234.08	$234.10	$234.10
Purchase #6	$224.53	6.136%	$238.3072	$238.31	$238.30	$238.30
Purchase #7	$19.32	6.555%	$20.5864	$20.59	$20.60	$20.60
7 purchase totals =	$874.61		$950.8894	$950.90	$950.95	$951.00