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	$181.52	10.469%	$200.5233	$200.52	$200.50	$200.50
Purchase #2	$80.94	4.520%	$84.5985	$84.60	$84.60	$84.60
Purchase #3	$195.64	10.505%	$216.192	$216.19	$216.20	$216.20
Purchase #4	$216.86	7.732%	$233.6276	$233.63	$233.65	$233.60
Purchase #5	$98.59	9.601%	$108.0556	$108.06	$108.05	$108.10
Purchase #6	$164.47	5.151%	$172.9418	$172.94	$172.95	$172.90
Purchase #7	$18.67	3.689%	$19.3587	$19.36	$19.35	$19.40
7 purchase totals =	$956.69		$1,035.2975	$1,035.30	$1,035.30	$1,035.30