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	$96.74	10.463%	$106.8619	$106.86	$106.85	$106.90
Purchase #2	$175.66	3.233%	$181.3391	$181.34	$181.35	$181.30
Purchase #3	$177.40	3.677%	$183.923	$183.92	$183.90	$183.90
Purchase #4	$240.55	13.735%	$273.5895	$273.59	$273.60	$273.60
Purchase #5	$39.54	10.210%	$43.577	$43.58	$43.60	$43.60
Purchase #6	$210.30	13.479%	$238.6463	$238.65	$238.65	$238.60
Purchase #7	$38.31	12.635%	$43.1505	$43.15	$43.15	$43.20
7 purchase totals =	$978.50		$1,071.0873	$1,071.09	$1,071.10	$1,071.10