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	$211.64	7.452%	$227.4114	$227.41	$227.40	$227.40
Purchase #2	$67.97	3.622%	$70.4319	$70.43	$70.45	$70.40
Purchase #3	$118.56	7.508%	$127.4615	$127.46	$127.45	$127.50
Purchase #4	$105.33	13.468%	$119.5158	$119.52	$119.50	$119.50
Purchase #5	$193.59	8.236%	$209.5341	$209.53	$209.55	$209.50
Purchase #6	$217.89	11.349%	$242.6183	$242.62	$242.60	$242.60
Purchase #7	$14.64	8.816%	$15.9307	$15.93	$15.95	$15.90
7 purchase totals =	$929.62		$1,012.9037	$1,012.90	$1,012.90	$1,012.80