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	$100.88	7.515%	$108.4611	$108.46	$108.45	$108.50
Purchase #2	$54.52	8.263%	$59.025	$59.03	$59.05	$59.00
Purchase #3	$175.65	11.292%	$195.4844	$195.48	$195.50	$195.50
Purchase #4	$77.80	7.474%	$83.6148	$83.61	$83.60	$83.60
Purchase #5	$158.82	13.257%	$179.8748	$179.87	$179.85	$179.90
Purchase #6	$122.38	6.233%	$130.0079	$130.01	$130.00	$130.00
Purchase #7	$197.33	10.486%	$218.022	$218.02	$218.00	$218.00
7 purchase totals =	$887.38		$974.4900	$974.48	$974.45	$974.50