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	$228.80	3.465%	$236.7279	$236.73	$236.75	$236.70
Purchase #2	$20.34	4.658%	$21.2874	$21.29	$21.30	$21.30
Purchase #3	$75.76	10.363%	$83.611	$83.61	$83.60	$83.60
Purchase #4	$137.90	3.181%	$142.2866	$142.29	$142.30	$142.30
Purchase #5	$151.95	9.689%	$166.6724	$166.67	$166.65	$166.70
Purchase #6	$224.27	11.157%	$249.2918	$249.29	$249.30	$249.30
Purchase #7	$58.76	6.430%	$62.5383	$62.54	$62.55	$62.50
7 purchase totals =	$897.78		$962.4154	$962.42	$962.45	$962.40