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	$174.96	9.139%	$190.9496	$190.95	$190.95	$190.90
Purchase #2	$38.67	9.128%	$42.1998	$42.20	$42.20	$42.20
Purchase #3	$33.34	11.503%	$37.1751	$37.18	$37.20	$37.20
Purchase #4	$233.32	3.224%	$240.8422	$240.84	$240.85	$240.80
Purchase #5	$228.86	8.381%	$248.0408	$248.04	$248.05	$248.00
Purchase #6	$40.47	11.182%	$44.9954	$45.00	$45.00	$45.00
Purchase #7	$244.82	5.715%	$258.8115	$258.81	$258.80	$258.80
7 purchase totals =	$994.44		$1,063.0144	$1,063.02	$1,063.05	$1,062.90