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	$136.28	10.601%	$150.727	$150.73	$150.75	$150.70
Purchase #2	$111.47	9.782%	$122.374	$122.37	$122.35	$122.40
Purchase #3	$41.96	7.846%	$45.2522	$45.25	$45.25	$45.30
Purchase #4	$76.67	7.215%	$82.2017	$82.20	$82.20	$82.20
Purchase #5	$148.46	13.564%	$168.5971	$168.60	$168.60	$168.60
Purchase #6	$31.57	3.586%	$32.7021	$32.70	$32.70	$32.70
Purchase #7	$109.94	12.228%	$123.3835	$123.38	$123.40	$123.40
7 purchase totals =	$656.35		$725.2376	$725.23	$725.25	$725.30