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	$146.28	5.175%	$153.85	$153.85	$153.85	$153.90
Purchase #2	$210.66	7.599%	$226.6681	$226.67	$226.65	$226.70
Purchase #3	$108.96	9.229%	$119.0159	$119.02	$119.00	$119.00
Purchase #4	$204.78	6.766%	$218.6354	$218.64	$218.65	$218.60
Purchase #5	$119.70	6.362%	$127.3153	$127.32	$127.30	$127.30
Purchase #6	$117.80	8.305%	$127.5833	$127.58	$127.60	$127.60
Purchase #7	$37.78	8.384%	$40.9475	$40.95	$40.95	$40.90
7 purchase totals =	$945.96		$1,014.0155	$1,014.03	$1,014.00	$1,014.00