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	$109.99	4.857%	$115.3322	$115.33	$115.35	$115.30
Purchase #2	$88.56	6.122%	$93.9816	$93.98	$94.00	$94.00
Purchase #3	$138.50	9.391%	$151.5065	$151.51	$151.50	$151.50
Purchase #4	$135.45	6.689%	$144.5103	$144.51	$144.50	$144.50
Purchase #5	$119.52	6.435%	$127.2111	$127.21	$127.20	$127.20
Purchase #6	$240.78	6.473%	$256.3657	$256.37	$256.35	$256.40
Purchase #7	$131.89	11.301%	$146.7949	$146.79	$146.80	$146.80
7 purchase totals =	$964.69		$1,035.7023	$1,035.70	$1,035.70	$1,035.70