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	$195.72	7.755%	$210.8981	$210.90	$210.90	$210.90
Purchase #2	$206.88	4.156%	$215.4779	$215.48	$215.50	$215.50
Purchase #3	$207.61	9.345%	$227.0112	$227.01	$227.00	$227.00
Purchase #4	$76.51	8.328%	$82.8818	$82.88	$82.90	$82.90
Purchase #5	$124.63	10.738%	$138.0128	$138.01	$138.00	$138.00
Purchase #6	$40.81	11.668%	$45.5717	$45.57	$45.55	$45.60
Purchase #7	$244.84	4.778%	$256.5385	$256.54	$256.55	$256.50
7 purchase totals =	$1,097.00		$1,176.3920	$1,176.39	$1,176.40	$1,176.40