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	$196.48	7.835%	$211.8742	$211.87	$211.85	$211.90
Purchase #2	$169.78	8.527%	$184.2571	$184.26	$184.25	$184.30
Purchase #3	$61.98	8.112%	$67.0078	$67.01	$67.00	$67.00
Purchase #4	$200.64	7.350%	$215.387	$215.39	$215.40	$215.40
Purchase #5	$49.81	7.166%	$53.3794	$53.38	$53.40	$53.40
Purchase #6	$96.30	12.557%	$108.3924	$108.39	$108.40	$108.40
Purchase #7	$6.84	9.252%	$7.4728	$7.47	$7.45	$7.50
7 purchase totals =	$781.83		$847.7707	$847.77	$847.75	$847.90