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	$13.97	5.715%	$14.7684	$14.77	$14.75	$14.80
Purchase #2	$186.83	4.258%	$194.7852	$194.79	$194.80	$194.80
Purchase #3	$214.40	4.712%	$224.5025	$224.50	$224.50	$224.50
Purchase #4	$227.88	12.292%	$255.891	$255.89	$255.90	$255.90
Purchase #5	$209.67	9.811%	$230.2407	$230.24	$230.25	$230.20
Purchase #6	$167.31	13.605%	$190.0725	$190.07	$190.05	$190.10
Purchase #7	$138.45	5.696%	$146.3361	$146.34	$146.35	$146.30
7 purchase totals =	$1,158.51		$1,256.5964	$1,256.60	$1,256.60	$1,256.60