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	$141.60	8.562%	$153.7238	$153.72	$153.70	$153.70
Purchase #2	$150.26	9.791%	$164.972	$164.97	$164.95	$165.00
Purchase #3	$191.31	9.528%	$209.538	$209.54	$209.55	$209.50
Purchase #4	$110.55	10.107%	$121.7233	$121.72	$121.70	$121.70
Purchase #5	$79.92	3.160%	$82.4455	$82.45	$82.45	$82.40
Purchase #6	$138.78	10.256%	$153.0133	$153.01	$153.00	$153.00
Purchase #7	$215.90	4.773%	$226.2049	$226.20	$226.20	$226.20
7 purchase totals =	$1,028.32		$1,111.6208	$1,111.61	$1,111.55	$1,111.50