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	$116.87	12.254%	$131.1912	$131.19	$131.20	$131.20
Purchase #2	$13.90	6.364%	$14.7846	$14.78	$14.80	$14.80
Purchase #3	$175.44	6.817%	$187.3997	$187.40	$187.40	$187.40
Purchase #4	$174.44	4.677%	$182.5986	$182.60	$182.60	$182.60
Purchase #5	$219.79	11.856%	$245.8483	$245.85	$245.85	$245.80
Purchase #6	$238.29	7.285%	$255.6494	$255.65	$255.65	$255.60
Purchase #7	$73.78	5.782%	$78.046	$78.05	$78.05	$78.00
7 purchase totals =	$1,012.51		$1,095.5178	$1,095.52	$1,095.55	$1,095.40