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	$109.46	4.176%	$114.031	$114.03	$114.05	$114.00
Purchase #2	$234.57	10.740%	$259.7628	$259.76	$259.75	$259.80
Purchase #3	$157.42	6.758%	$168.0584	$168.06	$168.05	$168.10
Purchase #4	$37.43	6.379%	$39.8177	$39.82	$39.80	$39.80
Purchase #5	$42.96	5.544%	$45.3417	$45.34	$45.35	$45.30
Purchase #6	$143.94	8.663%	$156.4095	$156.41	$156.40	$156.40
Purchase #7	$198.51	5.209%	$208.8504	$208.85	$208.85	$208.90
7 purchase totals =	$924.29		$992.2715	$992.27	$992.25	$992.30