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	$117.34	11.757%	$131.1357	$131.14	$131.15	$131.10
Purchase #2	$32.61	10.521%	$36.0409	$36.04	$36.05	$36.00
Purchase #3	$83.39	10.376%	$92.0425	$92.04	$92.05	$92.00
Purchase #4	$178.93	6.854%	$191.1939	$191.19	$191.20	$191.20
Purchase #5	$206.25	7.588%	$221.9003	$221.90	$221.90	$221.90
Purchase #6	$215.83	11.757%	$241.2051	$241.21	$241.20	$241.20
Purchase #7	$138.97	10.488%	$153.5452	$153.55	$153.55	$153.50
7 purchase totals =	$973.32		$1,067.0636	$1,067.07	$1,067.10	$1,066.90