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	$52.48	11.164%	$58.3389	$58.34	$58.35	$58.30
Purchase #2	$12.26	10.116%	$13.5002	$13.50	$13.50	$13.50
Purchase #3	$39.61	9.113%	$43.2197	$43.22	$43.20	$43.20
Purchase #4	$179.39	9.354%	$196.1701	$196.17	$196.15	$196.20
Purchase #5	$50.44	3.200%	$52.0541	$52.05	$52.05	$52.10
Purchase #6	$67.69	7.623%	$72.85	$72.85	$72.85	$72.90
Purchase #7	$14.66	7.545%	$15.7661	$15.77	$15.75	$15.80
7 purchase totals =	$416.53		$451.8991	$451.90	$451.85	$452.00