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	$169.28	12.514%	$190.4637	$190.46	$190.45	$190.50
Purchase #2	$160.78	7.474%	$172.7967	$172.80	$172.80	$172.80
Purchase #3	$127.77	11.293%	$142.1991	$142.20	$142.20	$142.20
Purchase #4	$190.46	11.205%	$211.801	$211.80	$211.80	$211.80
Purchase #5	$192.85	6.323%	$205.0439	$205.04	$205.05	$205.00
Purchase #6	$219.44	6.273%	$233.2055	$233.21	$233.20	$233.20
Purchase #7	$222.72	7.104%	$238.542	$238.54	$238.55	$238.50
7 purchase totals =	$1,283.30		$1,394.0519	$1,394.05	$1,394.05	$1,394.00