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	$82.85	3.785%	$85.9859	$85.99	$86.00	$86.00
Purchase #2	$18.90	9.656%	$20.725	$20.73	$20.75	$20.70
Purchase #3	$162.78	7.527%	$175.0325	$175.03	$175.05	$175.00
Purchase #4	$113.45	8.518%	$123.1137	$123.11	$123.10	$123.10
Purchase #5	$244.42	4.262%	$254.8372	$254.84	$254.85	$254.80
Purchase #6	$82.73	7.673%	$89.0779	$89.08	$89.10	$89.10
Purchase #7	$213.29	4.451%	$222.7835	$222.78	$222.80	$222.80
7 purchase totals =	$918.42		$971.5557	$971.56	$971.65	$971.50