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	$181.55	8.546%	$197.0653	$197.07	$197.05	$197.10
Purchase #2	$105.48	6.871%	$112.7275	$112.73	$112.75	$112.70
Purchase #3	$52.50	9.709%	$57.5972	$57.60	$57.60	$57.60
Purchase #4	$63.73	6.486%	$67.8635	$67.86	$67.85	$67.90
Purchase #5	$53.63	5.257%	$56.4493	$56.45	$56.45	$56.40
Purchase #6	$55.30	13.359%	$62.6875	$62.69	$62.70	$62.70
Purchase #7	$64.53	12.741%	$72.7518	$72.75	$72.75	$72.80
7 purchase totals =	$576.72		$627.1421	$627.15	$627.15	$627.20