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	$94.84	3.444%	$98.1063	$98.11	$98.10	$98.10
Purchase #2	$183.64	4.562%	$192.0177	$192.02	$192.00	$192.00
Purchase #3	$164.80	10.486%	$182.0809	$182.08	$182.10	$182.10
Purchase #4	$11.65	7.162%	$12.4844	$12.48	$12.50	$12.50
Purchase #5	$38.81	7.260%	$41.6276	$41.63	$41.65	$41.60
Purchase #6	$37.54	6.353%	$39.9249	$39.92	$39.90	$39.90
Purchase #7	$175.60	11.781%	$196.2874	$196.29	$196.30	$196.30
7 purchase totals =	$706.88		$762.5292	$762.53	$762.55	$762.50