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	$177.80	4.201%	$185.2694	$185.27	$185.25	$185.30
Purchase #2	$150.83	11.119%	$167.6008	$167.60	$167.60	$167.60
Purchase #3	$94.83	11.136%	$105.3903	$105.39	$105.40	$105.40
Purchase #4	$209.58	11.264%	$233.1871	$233.19	$233.20	$233.20
Purchase #5	$220.93	5.830%	$233.8102	$233.81	$233.80	$233.80
Purchase #6	$55.95	13.660%	$63.5928	$63.59	$63.60	$63.60
Purchase #7	$42.28	6.427%	$44.9973	$45.00	$45.00	$45.00
7 purchase totals =	$952.20		$1,033.8479	$1,033.85	$1,033.85	$1,033.90