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	$169.53	3.849%	$176.0552	$176.06	$176.05	$176.10
Purchase #2	$39.27	3.132%	$40.4999	$40.50	$40.50	$40.50
Purchase #3	$89.43	10.156%	$98.5125	$98.51	$98.50	$98.50
Purchase #4	$123.48	11.569%	$137.7654	$137.77	$137.75	$137.80
Purchase #5	$203.65	7.253%	$218.4207	$218.42	$218.40	$218.40
Purchase #6	$177.96	4.180%	$185.3987	$185.40	$185.40	$185.40
Purchase #7	$135.51	13.361%	$153.6155	$153.62	$153.60	$153.60
7 purchase totals =	$938.83		$1,010.2679	$1,010.28	$1,010.20	$1,010.30