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	$38.84	11.590%	$43.3416	$43.34	$43.35	$43.30
Purchase #2	$192.45	7.496%	$206.8761	$206.88	$206.90	$206.90
Purchase #3	$224.85	9.130%	$245.3788	$245.38	$245.40	$245.40
Purchase #4	$118.78	5.134%	$124.8782	$124.88	$124.90	$124.90
Purchase #5	$49.34	7.752%	$53.1648	$53.16	$53.15	$53.20
Purchase #6	$95.29	3.128%	$98.2707	$98.27	$98.25	$98.30
Purchase #7	$222.80	13.763%	$253.464	$253.46	$253.45	$253.50
7 purchase totals =	$942.35		$1,025.3742	$1,025.37	$1,025.40	$1,025.50