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	$88.50	11.419%	$98.6058	$98.61	$98.60	$98.60
Purchase #2	$75.65	8.475%	$82.0613	$82.06	$82.05	$82.10
Purchase #3	$177.28	7.382%	$190.3668	$190.37	$190.35	$190.40
Purchase #4	$228.57	5.684%	$241.5619	$241.56	$241.55	$241.60
Purchase #5	$91.38	4.743%	$95.7142	$95.71	$95.70	$95.70
Purchase #6	$211.52	12.784%	$238.5607	$238.56	$238.55	$238.60
Purchase #7	$134.48	7.758%	$144.913	$144.91	$144.90	$144.90
7 purchase totals =	$1,007.38		$1,091.7837	$1,091.78	$1,091.70	$1,091.90