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	$117.47	8.445%	$127.3903	$127.39	$127.40	$127.40
Purchase #2	$214.35	5.364%	$225.8477	$225.85	$225.85	$225.80
Purchase #3	$84.40	6.444%	$89.8387	$89.84	$89.85	$89.80
Purchase #4	$186.81	13.858%	$212.6981	$212.70	$212.70	$212.70
Purchase #5	$76.57	10.425%	$84.5524	$84.55	$84.55	$84.60
Purchase #6	$9.33	11.866%	$10.4371	$10.44	$10.45	$10.40
Purchase #7	$110.54	11.801%	$123.5848	$123.58	$123.60	$123.60
7 purchase totals =	$799.47		$874.3491	$874.35	$874.40	$874.30