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	$44.47	7.872%	$47.9707	$47.97	$47.95	$48.00
Purchase #2	$89.46	4.364%	$93.364	$93.36	$93.35	$93.40
Purchase #3	$110.34	11.791%	$123.3502	$123.35	$123.35	$123.40
Purchase #4	$85.34	8.845%	$92.8883	$92.89	$92.90	$92.90
Purchase #5	$58.62	6.702%	$62.5487	$62.55	$62.55	$62.50
Purchase #6	$39.60	7.139%	$42.427	$42.43	$42.45	$42.40
Purchase #7	$194.63	12.269%	$218.5092	$218.51	$218.50	$218.50
7 purchase totals =	$622.46		$681.0581	$681.06	$681.05	$681.10