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	$191.95	9.302%	$209.8052	$209.81	$209.80	$209.80
Purchase #2	$39.40	8.679%	$42.8195	$42.82	$42.80	$42.80
Purchase #3	$66.77	7.176%	$71.5614	$71.56	$71.55	$71.60
Purchase #4	$156.83	4.465%	$163.8325	$163.83	$163.85	$163.80
Purchase #5	$71.44	10.393%	$78.8648	$78.86	$78.85	$78.90
Purchase #6	$248.92	6.696%	$265.5877	$265.59	$265.60	$265.60
Purchase #7	$185.39	9.254%	$202.546	$202.55	$202.55	$202.50
7 purchase totals =	$960.70		$1,035.0171	$1,035.02	$1,035.00	$1,035.00