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	$141.60	13.394%	$160.5659	$160.57	$160.55	$160.60
Purchase #2	$178.44	7.488%	$191.8016	$191.80	$191.80	$191.80
Purchase #3	$73.59	6.526%	$78.3925	$78.39	$78.40	$78.40
Purchase #4	$141.51	7.509%	$152.136	$152.14	$152.15	$152.10
Purchase #5	$241.38	7.363%	$259.1528	$259.15	$259.15	$259.20
Purchase #6	$98.48	7.147%	$105.5184	$105.52	$105.50	$105.50
Purchase #7	$192.43	10.356%	$212.3581	$212.36	$212.35	$212.40
7 purchase totals =	$1,067.43		$1,159.9253	$1,159.93	$1,159.90	$1,160.00