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	$86.52	3.865%	$89.864	$89.86	$89.85	$89.90
Purchase #2	$49.36	12.419%	$55.49	$55.49	$55.50	$55.50
Purchase #3	$178.27	12.443%	$200.4521	$200.45	$200.45	$200.50
Purchase #4	$240.64	7.725%	$259.2294	$259.23	$259.25	$259.20
Purchase #5	$209.55	11.798%	$234.2727	$234.27	$234.25	$234.30
Purchase #6	$78.86	10.804%	$87.38	$87.38	$87.40	$87.40
Purchase #7	$213.56	4.432%	$223.025	$223.03	$223.05	$223.00
7 purchase totals =	$1,056.76		$1,149.7132	$1,149.71	$1,149.75	$1,149.80