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	$219.64	4.602%	$229.7478	$229.75	$229.75	$229.70
Purchase #2	$233.54	10.215%	$257.3961	$257.40	$257.40	$257.40
Purchase #3	$48.72	7.415%	$52.3326	$52.33	$52.35	$52.30
Purchase #4	$64.51	5.275%	$67.9129	$67.91	$67.90	$67.90
Purchase #5	$54.65	4.314%	$57.0076	$57.01	$57.00	$57.00
Purchase #6	$161.87	10.861%	$179.4507	$179.45	$179.45	$179.50
Purchase #7	$229.47	5.260%	$241.5401	$241.54	$241.55	$241.50
7 purchase totals =	$1,012.40		$1,085.3878	$1,085.39	$1,085.40	$1,085.30