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	$222.88	11.202%	$247.847	$247.85	$247.85	$247.80
Purchase #2	$200.96	10.678%	$222.4185	$222.42	$222.40	$222.40
Purchase #3	$172.38	5.871%	$182.5004	$182.50	$182.50	$182.50
Purchase #4	$42.27	7.453%	$45.4204	$45.42	$45.40	$45.40
Purchase #5	$41.80	7.524%	$44.945	$44.95	$44.95	$44.90
Purchase #6	$179.95	11.462%	$200.5759	$200.58	$200.60	$200.60
Purchase #7	$244.86	9.817%	$268.8979	$268.90	$268.90	$268.90
7 purchase totals =	$1,105.10		$1,212.6051	$1,212.62	$1,212.60	$1,212.50