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	$184.25	6.411%	$196.0623	$196.06	$196.05	$196.10
Purchase #2	$21.73	11.385%	$24.204	$24.20	$24.20	$24.20
Purchase #3	$96.38	5.116%	$101.3108	$101.31	$101.30	$101.30
Purchase #4	$28.76	3.724%	$29.831	$29.83	$29.85	$29.80
Purchase #5	$159.85	5.648%	$168.8783	$168.88	$168.90	$168.90
Purchase #6	$221.88	9.800%	$243.6242	$243.62	$243.60	$243.60
Purchase #7	$222.77	5.354%	$234.6971	$234.70	$234.70	$234.70
7 purchase totals =	$935.62		$998.6077	$998.60	$998.60	$998.60