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	$182.47	4.204%	$190.141	$190.14	$190.15	$190.10
Purchase #2	$158.49	13.654%	$180.1302	$180.13	$180.15	$180.10
Purchase #3	$43.72	6.212%	$46.4359	$46.44	$46.45	$46.40
Purchase #4	$37.92	6.817%	$40.505	$40.51	$40.50	$40.50
Purchase #5	$207.71	3.214%	$214.3858	$214.39	$214.40	$214.40
Purchase #6	$229.61	13.696%	$261.0574	$261.06	$261.05	$261.10
Purchase #7	$150.51	13.693%	$171.1193	$171.12	$171.10	$171.10
7 purchase totals =	$1,010.43		$1,103.7746	$1,103.79	$1,103.80	$1,103.70