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	$145.99	7.871%	$157.4809	$157.48	$157.50	$157.50
Purchase #2	$54.34	12.749%	$61.2678	$61.27	$61.25	$61.30
Purchase #3	$75.97	8.606%	$82.508	$82.51	$82.50	$82.50
Purchase #4	$101.37	4.574%	$106.0067	$106.01	$106.00	$106.00
Purchase #5	$240.34	10.376%	$265.2777	$265.28	$265.30	$265.30
Purchase #6	$234.49	9.212%	$256.0912	$256.09	$256.10	$256.10
Purchase #7	$238.71	12.214%	$267.866	$267.87	$267.85	$267.90
7 purchase totals =	$1,091.21		$1,196.4983	$1,196.51	$1,196.50	$1,196.60