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	$207.32	9.801%	$227.6394	$227.64	$227.65	$227.60
Purchase #2	$146.50	11.700%	$163.6405	$163.64	$163.65	$163.60
Purchase #3	$103.87	10.121%	$114.3827	$114.38	$114.40	$114.40
Purchase #4	$248.38	10.111%	$273.4937	$273.49	$273.50	$273.50
Purchase #5	$51.81	3.222%	$53.4793	$53.48	$53.50	$53.50
Purchase #6	$171.54	9.868%	$188.4676	$188.47	$188.45	$188.50
Purchase #7	$10.80	6.134%	$11.4625	$11.46	$11.45	$11.50
7 purchase totals =	$940.22		$1,032.5657	$1,032.56	$1,032.60	$1,032.60