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	$195.61	12.222%	$219.5175	$219.52	$219.50	$219.50
Purchase #2	$119.40	10.839%	$132.3418	$132.34	$132.35	$132.30
Purchase #3	$202.51	6.368%	$215.4058	$215.41	$215.40	$215.40
Purchase #4	$112.93	11.747%	$126.1959	$126.20	$126.20	$126.20
Purchase #5	$96.72	9.137%	$105.5573	$105.56	$105.55	$105.60
Purchase #6	$130.93	13.361%	$148.4236	$148.42	$148.40	$148.40
Purchase #7	$65.87	4.113%	$68.5792	$68.58	$68.60	$68.60
7 purchase totals =	$923.97		$1,016.0211	$1,016.03	$1,016.00	$1,016.00