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	$201.40	13.164%	$227.9123	$227.91	$227.90	$227.90
Purchase #2	$81.25	4.682%	$85.0541	$85.05	$85.05	$85.10
Purchase #3	$163.63	11.591%	$182.5964	$182.60	$182.60	$182.60
Purchase #4	$113.78	7.629%	$122.4603	$122.46	$122.45	$122.50
Purchase #5	$31.33	3.788%	$32.5168	$32.52	$32.50	$32.50
Purchase #6	$100.73	3.737%	$104.4943	$104.49	$104.50	$104.50
Purchase #7	$250.80	6.589%	$267.3252	$267.33	$267.35	$267.30
7 purchase totals =	$942.92		$1,022.3594	$1,022.36	$1,022.35	$1,022.40