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	$76.76	12.754%	$86.55	$86.55	$86.55	$86.60
Purchase #2	$5.60	5.206%	$5.8915	$5.89	$5.90	$5.90
Purchase #3	$232.71	5.288%	$245.0157	$245.02	$245.00	$245.00
Purchase #4	$70.37	3.169%	$72.6	$72.60	$72.60	$72.60
Purchase #5	$134.74	4.718%	$141.097	$141.10	$141.10	$141.10
Purchase #6	$178.87	9.815%	$196.4261	$196.43	$196.45	$196.40
Purchase #7	$82.49	5.589%	$87.1004	$87.10	$87.10	$87.10
7 purchase totals =	$781.54		$834.6807	$834.69	$834.70	$834.70