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	$185.48	10.803%	$205.5174	$205.52	$205.50	$205.50
Purchase #2	$186.27	5.612%	$196.7235	$196.72	$196.70	$196.70
Purchase #3	$114.84	10.458%	$126.85	$126.85	$126.85	$126.90
Purchase #4	$108.39	11.447%	$120.7974	$120.80	$120.80	$120.80
Purchase #5	$101.89	10.517%	$112.6058	$112.61	$112.60	$112.60
Purchase #6	$145.82	11.321%	$162.3283	$162.33	$162.35	$162.30
Purchase #7	$79.44	9.357%	$86.8732	$86.87	$86.85	$86.90
7 purchase totals =	$922.13		$1,011.6956	$1,011.70	$1,011.65	$1,011.70