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	$148.50	11.517%	$165.6027	$165.60	$165.60	$165.60
Purchase #2	$169.31	6.144%	$179.7124	$179.71	$179.70	$179.70
Purchase #3	$244.47	7.196%	$262.0621	$262.06	$262.05	$262.10
Purchase #4	$72.62	6.785%	$77.5473	$77.55	$77.55	$77.50
Purchase #5	$158.68	6.468%	$168.9434	$168.94	$168.95	$168.90
Purchase #6	$30.71	5.808%	$32.4936	$32.49	$32.50	$32.50
Purchase #7	$218.88	13.578%	$248.5995	$248.60	$248.60	$248.60
7 purchase totals =	$1,043.17		$1,134.9610	$1,134.95	$1,134.95	$1,134.90