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	$92.85	10.527%	$102.6243	$102.62	$102.60	$102.60
Purchase #2	$144.95	4.541%	$151.5322	$151.53	$151.55	$151.50
Purchase #3	$105.71	8.388%	$114.577	$114.58	$114.60	$114.60
Purchase #4	$59.53	8.216%	$64.421	$64.42	$64.40	$64.40
Purchase #5	$250.98	4.108%	$261.2903	$261.29	$261.30	$261.30
Purchase #6	$146.34	12.249%	$164.2652	$164.27	$164.25	$164.30
Purchase #7	$158.67	4.513%	$165.8308	$165.83	$165.85	$165.80
7 purchase totals =	$959.03		$1,024.5408	$1,024.54	$1,024.55	$1,024.50