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	$161.37	4.765%	$169.0593	$169.06	$169.05	$169.10
Purchase #2	$217.48	3.474%	$225.0353	$225.04	$225.05	$225.00
Purchase #3	$110.89	11.293%	$123.4128	$123.41	$123.40	$123.40
Purchase #4	$241.62	5.151%	$254.0658	$254.07	$254.05	$254.10
Purchase #5	$118.67	12.578%	$133.5963	$133.60	$133.60	$133.60
Purchase #6	$224.66	13.640%	$255.3036	$255.30	$255.30	$255.30
Purchase #7	$214.96	3.780%	$223.0855	$223.09	$223.10	$223.10
7 purchase totals =	$1,289.65		$1,383.5586	$1,383.57	$1,383.55	$1,383.60