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	$148.72	9.129%	$162.2966	$162.30	$162.30	$162.30
Purchase #2	$105.90	12.871%	$119.5304	$119.53	$119.55	$119.50
Purchase #3	$98.31	11.696%	$109.8083	$109.81	$109.80	$109.80
Purchase #4	$196.31	4.541%	$205.2244	$205.22	$205.20	$205.20
Purchase #5	$141.74	10.821%	$157.0777	$157.08	$157.10	$157.10
Purchase #6	$160.75	9.632%	$176.2334	$176.23	$176.25	$176.20
Purchase #7	$147.49	6.410%	$156.9441	$156.94	$156.95	$156.90
7 purchase totals =	$999.22		$1,087.1149	$1,087.11	$1,087.15	$1,087.00