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	$187.52	12.535%	$211.0256	$211.03	$211.05	$211.00
Purchase #2	$150.52	7.473%	$161.7684	$161.77	$161.75	$161.80
Purchase #3	$109.81	12.558%	$123.5999	$123.60	$123.60	$123.60
Purchase #4	$196.83	11.131%	$218.7391	$218.74	$218.75	$218.70
Purchase #5	$153.49	4.731%	$160.7516	$160.75	$160.75	$160.80
Purchase #6	$108.48	10.853%	$120.2533	$120.25	$120.25	$120.30
Purchase #7	$78.97	4.273%	$82.3444	$82.34	$82.35	$82.30
7 purchase totals =	$985.62		$1,078.4823	$1,078.48	$1,078.50	$1,078.50