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	$152.34	13.442%	$172.8175	$172.82	$172.80	$172.80
Purchase #2	$85.46	4.407%	$89.2262	$89.23	$89.25	$89.20
Purchase #3	$101.93	11.345%	$113.494	$113.49	$113.50	$113.50
Purchase #4	$202.28	3.128%	$208.6073	$208.61	$208.60	$208.60
Purchase #5	$66.49	8.693%	$72.27	$72.27	$72.25	$72.30
Purchase #6	$230.96	6.869%	$246.8246	$246.82	$246.80	$246.80
Purchase #7	$183.83	8.382%	$199.2386	$199.24	$199.25	$199.20
7 purchase totals =	$1,023.29		$1,102.4782	$1,102.48	$1,102.45	$1,102.40