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	$222.73	8.620%	$241.9293	$241.93	$241.95	$241.90
Purchase #2	$79.75	11.784%	$89.1477	$89.15	$89.15	$89.10
Purchase #3	$31.51	13.664%	$35.8155	$35.82	$35.80	$35.80
Purchase #4	$169.43	10.824%	$187.7691	$187.77	$187.75	$187.80
Purchase #5	$104.65	9.807%	$114.913	$114.91	$114.90	$114.90
Purchase #6	$58.67	5.565%	$61.935	$61.94	$61.95	$61.90
Purchase #7	$193.42	11.734%	$216.1159	$216.12	$216.10	$216.10
7 purchase totals =	$860.16		$947.6255	$947.64	$947.60	$947.50