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	$151.66	10.516%	$167.6086	$167.61	$167.60	$167.60
Purchase #2	$47.97	7.568%	$51.6004	$51.60	$51.60	$51.60
Purchase #3	$70.63	12.774%	$79.6523	$79.65	$79.65	$79.70
Purchase #4	$165.60	11.692%	$184.962	$184.96	$184.95	$185.00
Purchase #5	$177.79	7.815%	$191.6843	$191.68	$191.70	$191.70
Purchase #6	$160.45	11.111%	$178.2776	$178.28	$178.30	$178.30
Purchase #7	$211.61	10.162%	$233.1138	$233.11	$233.10	$233.10
7 purchase totals =	$985.71		$1,086.8990	$1,086.89	$1,086.90	$1,087.00