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	$213.45	4.440%	$222.9272	$222.93	$222.95	$222.90
Purchase #2	$74.70	10.781%	$82.7534	$82.75	$82.75	$82.80
Purchase #3	$216.58	13.661%	$246.167	$246.17	$246.15	$246.20
Purchase #4	$75.73	10.374%	$83.5862	$83.59	$83.60	$83.60
Purchase #5	$11.49	12.479%	$12.9238	$12.92	$12.90	$12.90
Purchase #6	$184.74	7.670%	$198.9096	$198.91	$198.90	$198.90
Purchase #7	$214.35	5.224%	$225.5476	$225.55	$225.55	$225.50
7 purchase totals =	$991.04		$1,072.8148	$1,072.82	$1,072.80	$1,072.80