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	$162.53	7.545%	$174.7929	$174.79	$174.80	$174.80
Purchase #2	$95.62	7.241%	$102.5438	$102.54	$102.55	$102.50
Purchase #3	$198.56	6.527%	$211.52	$211.52	$211.50	$211.50
Purchase #4	$30.34	3.647%	$31.4465	$31.45	$31.45	$31.40
Purchase #5	$71.51	6.421%	$76.1017	$76.10	$76.10	$76.10
Purchase #6	$228.87	5.693%	$241.8996	$241.90	$241.90	$241.90
Purchase #7	$156.81	10.216%	$172.8297	$172.83	$172.85	$172.80
7 purchase totals =	$944.24		$1,011.1342	$1,011.13	$1,011.15	$1,011.00