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	$196.69	9.242%	$214.8681	$214.87	$214.85	$214.90
Purchase #2	$70.80	3.823%	$73.5067	$73.51	$73.50	$73.50
Purchase #3	$82.72	3.293%	$85.444	$85.44	$85.45	$85.40
Purchase #4	$191.90	11.276%	$213.5386	$213.54	$213.55	$213.50
Purchase #5	$172.62	7.654%	$185.8323	$185.83	$185.85	$185.80
Purchase #6	$112.48	11.114%	$124.981	$124.98	$125.00	$125.00
Purchase #7	$28.79	8.412%	$31.2118	$31.21	$31.20	$31.20
7 purchase totals =	$856.00		$929.3825	$929.38	$929.40	$929.30