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	$232.66	12.778%	$262.3893	$262.39	$262.40	$262.40
Purchase #2	$244.59	9.326%	$267.4005	$267.40	$267.40	$267.40
Purchase #3	$37.39	6.153%	$39.6906	$39.69	$39.70	$39.70
Purchase #4	$139.73	7.596%	$150.3439	$150.34	$150.35	$150.30
Purchase #5	$34.91	6.419%	$37.1509	$37.15	$37.15	$37.20
Purchase #6	$152.46	11.182%	$169.5081	$169.51	$169.50	$169.50
Purchase #7	$93.39	10.639%	$103.3258	$103.33	$103.35	$103.30
7 purchase totals =	$935.13		$1,029.8091	$1,029.81	$1,029.85	$1,029.80