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	$216.27	5.466%	$228.0913	$228.09	$228.10	$228.10
Purchase #2	$142.88	3.207%	$147.4622	$147.46	$147.45	$147.50
Purchase #3	$10.57	3.849%	$10.9768	$10.98	$11.00	$11.00
Purchase #4	$227.39	7.731%	$244.9695	$244.97	$244.95	$245.00
Purchase #5	$154.46	6.273%	$164.1493	$164.15	$164.15	$164.10
Purchase #6	$146.53	6.672%	$156.3065	$156.31	$156.30	$156.30
Purchase #7	$86.72	12.463%	$97.5279	$97.53	$97.55	$97.50
7 purchase totals =	$984.82		$1,049.4835	$1,049.49	$1,049.50	$1,049.50