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	$193.76	9.457%	$212.0839	$212.08	$212.10	$212.10
Purchase #2	$249.48	13.661%	$283.5615	$283.56	$283.55	$283.60
Purchase #3	$85.42	6.392%	$90.88	$90.88	$90.90	$90.90
Purchase #4	$50.53	6.145%	$53.6351	$53.64	$53.65	$53.60
Purchase #5	$218.55	10.814%	$242.184	$242.18	$242.20	$242.20
Purchase #6	$127.35	5.348%	$134.1607	$134.16	$134.15	$134.20
Purchase #7	$48.96	7.151%	$52.4611	$52.46	$52.45	$52.50
7 purchase totals =	$974.05		$1,068.9663	$1,068.96	$1,069.00	$1,069.10