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	$216.92	5.147%	$228.0849	$228.08	$228.10	$228.10
Purchase #2	$147.29	4.619%	$154.0933	$154.09	$154.10	$154.10
Purchase #3	$135.29	5.417%	$142.6187	$142.62	$142.60	$142.60
Purchase #4	$216.57	11.651%	$241.8026	$241.80	$241.80	$241.80
Purchase #5	$114.67	11.288%	$127.6139	$127.61	$127.60	$127.60
Purchase #6	$79.43	12.412%	$89.2889	$89.29	$89.30	$89.30
Purchase #7	$142.87	3.212%	$147.459	$147.46	$147.45	$147.50
7 purchase totals =	$1,053.04		$1,130.9613	$1,130.95	$1,130.95	$1,131.00