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	$197.85	12.427%	$222.4368	$222.44	$222.45	$222.40
Purchase #2	$182.46	9.834%	$200.4031	$200.40	$200.40	$200.40
Purchase #3	$123.95	12.496%	$139.4388	$139.44	$139.45	$139.40
Purchase #4	$142.53	5.765%	$150.7469	$150.75	$150.75	$150.70
Purchase #5	$206.96	9.378%	$226.3687	$226.37	$226.35	$226.40
Purchase #6	$47.95	11.487%	$53.458	$53.46	$53.45	$53.50
Purchase #7	$105.35	7.188%	$112.9226	$112.92	$112.90	$112.90
7 purchase totals =	$1,007.05		$1,105.7749	$1,105.78	$1,105.75	$1,105.70