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	$136.71	11.699%	$152.7037	$152.70	$152.70	$152.70
Purchase #2	$62.65	12.695%	$70.6034	$70.60	$70.60	$70.60
Purchase #3	$184.90	10.391%	$204.113	$204.11	$204.10	$204.10
Purchase #4	$183.53	6.781%	$195.9752	$195.98	$196.00	$196.00
Purchase #5	$164.69	13.814%	$187.4403	$187.44	$187.45	$187.40
Purchase #6	$29.54	10.750%	$32.7156	$32.72	$32.70	$32.70
Purchase #7	$185.47	12.658%	$208.9468	$208.95	$208.95	$208.90
7 purchase totals =	$947.49		$1,052.4980	$1,052.50	$1,052.50	$1,052.40