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	$49.44	9.124%	$53.9509	$53.95	$53.95	$54.00
Purchase #2	$52.72	4.288%	$54.9806	$54.98	$55.00	$55.00
Purchase #3	$195.82	3.587%	$202.8441	$202.84	$202.85	$202.80
Purchase #4	$43.50	4.417%	$45.4214	$45.42	$45.40	$45.40
Purchase #5	$137.83	5.443%	$145.3321	$145.33	$145.35	$145.30
Purchase #6	$9.78	6.225%	$10.3888	$10.39	$10.40	$10.40
Purchase #7	$223.31	11.517%	$249.0286	$249.03	$249.05	$249.00
7 purchase totals =	$712.40		$761.9465	$761.94	$762.00	$761.90