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	$119.35	7.128%	$127.8573	$127.86	$127.85	$127.90
Purchase #2	$86.94	3.364%	$89.8647	$89.86	$89.85	$89.90
Purchase #3	$61.71	10.108%	$67.9476	$67.95	$67.95	$67.90
Purchase #4	$36.99	13.758%	$42.0791	$42.08	$42.10	$42.10
Purchase #5	$244.50	3.179%	$252.2727	$252.27	$252.25	$252.30
Purchase #6	$242.72	11.758%	$271.259	$271.26	$271.25	$271.30
Purchase #7	$202.28	3.391%	$209.1393	$209.14	$209.15	$209.10
7 purchase totals =	$994.49		$1,060.4197	$1,060.42	$1,060.40	$1,060.50