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	$150.92	4.285%	$157.3869	$157.39	$157.40	$157.40
Purchase #2	$19.73	4.322%	$20.5827	$20.58	$20.60	$20.60
Purchase #3	$125.53	4.803%	$131.5592	$131.56	$131.55	$131.60
Purchase #4	$244.92	12.800%	$276.2698	$276.27	$276.25	$276.30
Purchase #5	$89.40	6.806%	$95.4846	$95.48	$95.50	$95.50
Purchase #6	$212.91	13.508%	$241.6699	$241.67	$241.65	$241.70
Purchase #7	$135.63	12.193%	$152.1674	$152.17	$152.15	$152.20
7 purchase totals =	$979.04		$1,075.1205	$1,075.12	$1,075.10	$1,075.30