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	$42.89	8.335%	$46.4649	$46.46	$46.45	$46.50
Purchase #2	$228.53	11.871%	$255.6588	$255.66	$255.65	$255.70
Purchase #3	$149.39	10.160%	$164.568	$164.57	$164.55	$164.60
Purchase #4	$52.47	9.447%	$57.4268	$57.43	$57.45	$57.40
Purchase #5	$73.75	9.187%	$80.5254	$80.53	$80.55	$80.50
Purchase #6	$153.80	5.481%	$162.2298	$162.23	$162.25	$162.20
Purchase #7	$248.69	5.453%	$262.2511	$262.25	$262.25	$262.30
7 purchase totals =	$949.52		$1,029.1248	$1,029.13	$1,029.15	$1,029.20