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	$174.32	5.470%	$183.8553	$183.86	$183.85	$183.90
Purchase #2	$166.71	3.377%	$172.3398	$172.34	$172.35	$172.30
Purchase #3	$218.54	8.707%	$237.5683	$237.57	$237.55	$237.60
Purchase #4	$102.78	13.417%	$116.57	$116.57	$116.55	$116.60
Purchase #5	$136.83	5.516%	$144.3775	$144.38	$144.40	$144.40
Purchase #6	$157.34	13.773%	$179.0104	$179.01	$179.00	$179.00
Purchase #7	$15.46	11.193%	$17.1904	$17.19	$17.20	$17.20
7 purchase totals =	$971.98		$1,050.9117	$1,050.92	$1,050.90	$1,051.00