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	$181.26	8.445%	$196.5674	$196.57	$196.55	$196.60
Purchase #2	$27.72	11.654%	$30.9505	$30.95	$30.95	$31.00
Purchase #3	$221.44	12.814%	$249.8153	$249.82	$249.80	$249.80
Purchase #4	$54.76	10.262%	$60.3795	$60.38	$60.40	$60.40
Purchase #5	$53.64	11.473%	$59.7941	$59.79	$59.80	$59.80
Purchase #6	$93.29	5.698%	$98.6057	$98.61	$98.60	$98.60
Purchase #7	$242.75	10.426%	$268.0591	$268.06	$268.05	$268.10
7 purchase totals =	$874.86		$964.1716	$964.18	$964.15	$964.30