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	$124.76	5.709%	$131.8825	$131.88	$131.90	$131.90
Purchase #2	$123.35	7.213%	$132.2472	$132.25	$132.25	$132.20
Purchase #3	$182.65	8.656%	$198.4602	$198.46	$198.45	$198.50
Purchase #4	$226.45	4.502%	$236.6448	$236.64	$236.65	$236.60
Purchase #5	$61.95	5.789%	$65.5363	$65.54	$65.55	$65.50
Purchase #6	$98.55	5.857%	$104.3221	$104.32	$104.30	$104.30
Purchase #7	$184.60	4.281%	$192.5027	$192.50	$192.50	$192.50
7 purchase totals =	$1,002.31		$1,061.5958	$1,061.59	$1,061.60	$1,061.50