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	$141.41	4.556%	$147.8526	$147.85	$147.85	$147.90
Purchase #2	$178.47	9.623%	$195.6442	$195.64	$195.65	$195.60
Purchase #3	$143.50	9.140%	$156.6159	$156.62	$156.60	$156.60
Purchase #4	$118.50	7.618%	$127.5273	$127.53	$127.55	$127.50
Purchase #5	$68.61	7.128%	$73.5005	$73.50	$73.50	$73.50
Purchase #6	$171.80	4.397%	$179.354	$179.35	$179.35	$179.40
Purchase #7	$173.43	12.538%	$195.1747	$195.17	$195.15	$195.20
7 purchase totals =	$995.72		$1,075.6692	$1,075.66	$1,075.65	$1,075.70