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	$212.40	4.477%	$221.9091	$221.91	$221.90	$221.90
Purchase #2	$70.64	4.629%	$73.9099	$73.91	$73.90	$73.90
Purchase #3	$96.51	6.203%	$102.4965	$102.50	$102.50	$102.50
Purchase #4	$169.36	10.351%	$186.8905	$186.89	$186.90	$186.90
Purchase #5	$54.99	11.613%	$61.376	$61.38	$61.40	$61.40
Purchase #6	$94.82	10.809%	$105.0691	$105.07	$105.05	$105.10
Purchase #7	$249.42	4.215%	$259.9331	$259.93	$259.95	$259.90
7 purchase totals =	$948.14		$1,011.5842	$1,011.59	$1,011.60	$1,011.60