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	$238.93	9.845%	$262.4527	$262.45	$262.45	$262.50
Purchase #2	$77.97	5.774%	$82.472	$82.47	$82.45	$82.50
Purchase #3	$171.32	7.730%	$184.563	$184.56	$184.55	$184.60
Purchase #4	$245.31	6.829%	$262.0622	$262.06	$262.05	$262.10
Purchase #5	$131.52	9.519%	$144.0394	$144.04	$144.05	$144.00
Purchase #6	$213.57	9.322%	$233.479	$233.48	$233.50	$233.50
Purchase #7	$175.44	8.790%	$190.8612	$190.86	$190.85	$190.90
7 purchase totals =	$1,254.06		$1,359.9295	$1,359.92	$1,359.90	$1,360.10