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	$206.85	3.491%	$214.0711	$214.07	$214.05	$214.10
Purchase #2	$65.52	12.137%	$73.4722	$73.47	$73.45	$73.50
Purchase #3	$139.53	9.158%	$152.3082	$152.31	$152.30	$152.30
Purchase #4	$236.53	9.322%	$258.5793	$258.58	$258.60	$258.60
Purchase #5	$84.75	12.757%	$95.5616	$95.56	$95.55	$95.60
Purchase #6	$175.28	5.749%	$185.3568	$185.36	$185.35	$185.40
Purchase #7	$178.61	12.446%	$200.8398	$200.84	$200.85	$200.80
7 purchase totals =	$1,087.07		$1,180.1890	$1,180.19	$1,180.15	$1,180.30