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	$146.54	7.545%	$157.5964	$157.60	$157.60	$157.60
Purchase #2	$143.49	5.276%	$151.0605	$151.06	$151.05	$151.10
Purchase #3	$40.76	6.376%	$43.3589	$43.36	$43.35	$43.40
Purchase #4	$184.72	12.315%	$207.4683	$207.47	$207.45	$207.50
Purchase #5	$103.36	6.363%	$109.9368	$109.94	$109.95	$109.90
Purchase #6	$90.67	8.781%	$98.6317	$98.63	$98.65	$98.60
Purchase #7	$231.78	10.638%	$256.4368	$256.44	$256.45	$256.40
7 purchase totals =	$941.32		$1,024.4894	$1,024.50	$1,024.50	$1,024.50