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	$115.34	8.567%	$125.2212	$125.22	$125.20	$125.20
Purchase #2	$190.31	11.125%	$211.482	$211.48	$211.50	$211.50
Purchase #3	$232.32	13.241%	$263.0815	$263.08	$263.10	$263.10
Purchase #4	$70.79	11.406%	$78.8643	$78.86	$78.85	$78.90
Purchase #5	$140.29	8.647%	$152.4209	$152.42	$152.40	$152.40
Purchase #6	$215.72	4.555%	$225.546	$225.55	$225.55	$225.50
Purchase #7	$54.72	4.551%	$57.2103	$57.21	$57.20	$57.20
7 purchase totals =	$1,019.49		$1,113.8262	$1,113.82	$1,113.80	$1,113.80