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	$214.38	8.824%	$233.2969	$233.30	$233.30	$233.30
Purchase #2	$236.32	11.179%	$262.7382	$262.74	$262.75	$262.70
Purchase #3	$48.89	11.132%	$54.3324	$54.33	$54.35	$54.30
Purchase #4	$101.72	12.696%	$114.6344	$114.63	$114.65	$114.60
Purchase #5	$132.62	6.199%	$140.8411	$140.84	$140.85	$140.80
Purchase #6	$137.67	10.782%	$152.5136	$152.51	$152.50	$152.50
Purchase #7	$199.45	3.223%	$205.8783	$205.88	$205.90	$205.90
7 purchase totals =	$1,071.05		$1,164.2349	$1,164.23	$1,164.30	$1,164.10