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	$112.26	11.377%	$125.0318	$125.03	$125.05	$125.00
Purchase #2	$190.43	3.255%	$196.6285	$196.63	$196.65	$196.60
Purchase #3	$180.91	13.518%	$205.3654	$205.37	$205.35	$205.40
Purchase #4	$51.79	13.576%	$58.821	$58.82	$58.80	$58.80
Purchase #5	$59.33	13.789%	$67.511	$67.51	$67.50	$67.50
Purchase #6	$51.83	3.393%	$53.5886	$53.59	$53.60	$53.60
Purchase #7	$39.69	4.430%	$41.4483	$41.45	$41.45	$41.40
7 purchase totals =	$686.24		$748.3946	$748.40	$748.40	$748.30