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	$150.78	10.841%	$167.1261	$167.13	$167.15	$167.10
Purchase #2	$214.40	8.661%	$232.9692	$232.97	$232.95	$233.00
Purchase #3	$38.88	5.385%	$40.9737	$40.97	$40.95	$41.00
Purchase #4	$235.68	11.394%	$262.5334	$262.53	$262.55	$262.50
Purchase #5	$209.83	13.860%	$238.9124	$238.91	$238.90	$238.90
Purchase #6	$166.86	3.459%	$172.6317	$172.63	$172.65	$172.60
Purchase #7	$241.94	7.231%	$259.4347	$259.43	$259.45	$259.40
7 purchase totals =	$1,258.37		$1,374.5812	$1,374.57	$1,374.60	$1,374.50