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	$200.65	9.385%	$219.481	$219.48	$219.50	$219.50
Purchase #2	$25.77	11.697%	$28.7843	$28.78	$28.80	$28.80
Purchase #3	$144.88	13.604%	$164.5895	$164.59	$164.60	$164.60
Purchase #4	$53.45	10.633%	$59.1333	$59.13	$59.15	$59.10
Purchase #5	$13.55	12.460%	$15.2383	$15.24	$15.25	$15.20
Purchase #6	$200.57	4.601%	$209.7982	$209.80	$209.80	$209.80
Purchase #7	$102.28	3.619%	$105.9815	$105.98	$106.00	$106.00
7 purchase totals =	$741.15		$803.0061	$803.00	$803.10	$803.00