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	$185.64	4.837%	$194.6194	$194.62	$194.60	$194.60
Purchase #2	$105.63	13.217%	$119.5911	$119.59	$119.60	$119.60
Purchase #3	$23.46	6.458%	$24.975	$24.98	$25.00	$25.00
Purchase #4	$112.72	13.255%	$127.661	$127.66	$127.65	$127.70
Purchase #5	$202.80	9.243%	$221.5448	$221.54	$221.55	$221.50
Purchase #6	$88.86	13.220%	$100.6073	$100.61	$100.60	$100.60
Purchase #7	$63.43	9.704%	$69.5852	$69.59	$69.60	$69.60
7 purchase totals =	$782.54		$858.5838	$858.59	$858.60	$858.60