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	$69.67	3.294%	$71.9649	$71.96	$71.95	$72.00
Purchase #2	$10.35	11.790%	$11.5703	$11.57	$11.55	$11.60
Purchase #3	$58.47	13.873%	$66.5815	$66.58	$66.60	$66.60
Purchase #4	$206.83	3.502%	$214.0732	$214.07	$214.05	$214.10
Purchase #5	$136.38	4.168%	$142.0643	$142.06	$142.05	$142.10
Purchase #6	$182.28	10.184%	$200.8434	$200.84	$200.85	$200.80
Purchase #7	$49.45	7.773%	$53.2937	$53.29	$53.30	$53.30
7 purchase totals =	$713.43		$760.3913	$760.37	$760.35	$760.50