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	$216.86	11.836%	$242.5275	$242.53	$242.55	$242.50
Purchase #2	$30.30	5.135%	$31.8559	$31.86	$31.85	$31.90
Purchase #3	$60.25	4.624%	$63.036	$63.04	$63.05	$63.00
Purchase #4	$101.96	3.108%	$105.1289	$105.13	$105.15	$105.10
Purchase #5	$245.31	7.418%	$263.5071	$263.51	$263.50	$263.50
Purchase #6	$190.44	4.246%	$198.5261	$198.53	$198.55	$198.50
Purchase #7	$102.71	3.598%	$106.4055	$106.41	$106.40	$106.40
7 purchase totals =	$947.83		$1,010.9870	$1,011.01	$1,011.05	$1,010.90