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	$209.84	11.430%	$233.8247	$233.82	$233.80	$233.80
Purchase #2	$30.39	4.388%	$31.7235	$31.72	$31.70	$31.70
Purchase #3	$130.93	10.241%	$144.3385	$144.34	$144.35	$144.30
Purchase #4	$168.46	6.725%	$179.7889	$179.79	$179.80	$179.80
Purchase #5	$182.53	12.533%	$205.4065	$205.41	$205.40	$205.40
Purchase #6	$187.76	13.131%	$212.4148	$212.41	$212.40	$212.40
Purchase #7	$141.65	9.146%	$154.6053	$154.61	$154.60	$154.60
7 purchase totals =	$1,051.56		$1,162.1022	$1,162.10	$1,162.05	$1,162.00