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	$47.52	13.229%	$53.8064	$53.81	$53.80	$53.80
Purchase #2	$65.47	7.661%	$70.4857	$70.49	$70.50	$70.50
Purchase #3	$14.99	5.601%	$15.8296	$15.83	$15.85	$15.80
Purchase #4	$88.27	11.637%	$98.542	$98.54	$98.55	$98.50
Purchase #5	$117.33	6.259%	$124.6737	$124.67	$124.65	$124.70
Purchase #6	$59.59	10.682%	$65.9554	$65.96	$65.95	$66.00
Purchase #7	$117.25	13.695%	$133.3074	$133.31	$133.30	$133.30
7 purchase totals =	$510.42		$562.6002	$562.61	$562.60	$562.60