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	$47.45	12.814%	$53.5302	$53.53	$53.55	$53.50
Purchase #2	$68.25	13.675%	$77.5832	$77.58	$77.60	$77.60
Purchase #3	$133.78	4.786%	$140.1827	$140.18	$140.20	$140.20
Purchase #4	$250.43	9.225%	$273.5322	$273.53	$273.55	$273.50
Purchase #5	$220.59	4.443%	$230.3908	$230.39	$230.40	$230.40
Purchase #6	$33.38	12.341%	$37.4994	$37.50	$37.50	$37.50
Purchase #7	$224.34	11.200%	$249.4661	$249.47	$249.45	$249.50
7 purchase totals =	$978.22		$1,062.1846	$1,062.18	$1,062.25	$1,062.20