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	$184.43	6.411%	$196.2538	$196.25	$196.25	$196.30
Purchase #2	$95.42	4.375%	$99.5946	$99.59	$99.60	$99.60
Purchase #3	$98.65	6.805%	$105.3631	$105.36	$105.35	$105.40
Purchase #4	$100.73	13.564%	$114.393	$114.39	$114.40	$114.40
Purchase #5	$176.74	7.535%	$190.0574	$190.06	$190.05	$190.10
Purchase #6	$168.40	5.371%	$177.4448	$177.44	$177.45	$177.40
Purchase #7	$209.70	12.379%	$235.6588	$235.66	$235.65	$235.70
7 purchase totals =	$1,034.07		$1,118.7655	$1,118.75	$1,118.75	$1,118.90