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	$216.68	7.110%	$232.0859	$232.09	$232.10	$232.10
Purchase #2	$137.99	4.483%	$144.1761	$144.18	$144.20	$144.20
Purchase #3	$150.45	9.263%	$164.3862	$164.39	$164.40	$164.40
Purchase #4	$180.80	10.104%	$199.068	$199.07	$199.05	$199.10
Purchase #5	$172.51	13.620%	$196.0059	$196.01	$196.00	$196.00
Purchase #6	$96.38	8.282%	$104.3622	$104.36	$104.35	$104.40
Purchase #7	$133.41	6.348%	$141.8789	$141.88	$141.90	$141.90
7 purchase totals =	$1,088.22		$1,181.9632	$1,181.98	$1,182.00	$1,182.10