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	$162.60	7.630%	$175.0064	$175.01	$175.00	$175.00
Purchase #2	$203.52	9.554%	$222.9643	$222.96	$222.95	$223.00
Purchase #3	$138.27	12.489%	$155.5385	$155.54	$155.55	$155.50
Purchase #4	$33.98	13.498%	$38.5666	$38.57	$38.55	$38.60
Purchase #5	$180.95	10.433%	$199.8285	$199.83	$199.85	$199.80
Purchase #6	$153.34	5.707%	$162.0911	$162.09	$162.10	$162.10
Purchase #7	$75.63	3.766%	$78.4782	$78.48	$78.50	$78.50
7 purchase totals =	$948.29		$1,032.4736	$1,032.48	$1,032.50	$1,032.50