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	$213.56	6.112%	$226.6128	$226.61	$226.60	$226.60
Purchase #2	$235.45	6.257%	$250.1821	$250.18	$250.20	$250.20
Purchase #3	$61.78	8.776%	$67.2018	$67.20	$67.20	$67.20
Purchase #4	$127.75	7.632%	$137.4999	$137.50	$137.50	$137.50
Purchase #5	$177.76	4.390%	$185.5637	$185.56	$185.55	$185.60
Purchase #6	$101.77	12.486%	$114.477	$114.48	$114.50	$114.50
Purchase #7	$156.71	5.724%	$165.6801	$165.68	$165.70	$165.70
7 purchase totals =	$1,074.78		$1,147.2174	$1,147.21	$1,147.25	$1,147.30