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	$43.44	11.387%	$48.3865	$48.39	$48.40	$48.40
Purchase #2	$224.93	7.805%	$242.4858	$242.49	$242.50	$242.50
Purchase #3	$99.62	13.265%	$112.8346	$112.83	$112.85	$112.80
Purchase #4	$119.83	6.606%	$127.746	$127.75	$127.75	$127.70
Purchase #5	$136.76	10.338%	$150.8982	$150.90	$150.90	$150.90
Purchase #6	$161.60	6.327%	$171.8244	$171.82	$171.80	$171.80
Purchase #7	$90.82	11.375%	$101.1508	$101.15	$101.15	$101.20
7 purchase totals =	$877.00		$955.3263	$955.33	$955.35	$955.30