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	$228.81	8.345%	$247.9042	$247.90	$247.90	$247.90
Purchase #2	$236.73	8.122%	$255.9572	$255.96	$255.95	$256.00
Purchase #3	$31.47	10.471%	$34.7652	$34.77	$34.75	$34.80
Purchase #4	$140.27	8.541%	$152.2505	$152.25	$152.25	$152.30
Purchase #5	$142.66	13.474%	$161.882	$161.88	$161.90	$161.90
Purchase #6	$203.76	11.434%	$227.0579	$227.06	$227.05	$227.10
Purchase #7	$60.32	12.571%	$67.9028	$67.90	$67.90	$67.90
7 purchase totals =	$1,044.02		$1,147.7198	$1,147.72	$1,147.70	$1,147.90