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	$206.64	3.530%	$213.9344	$213.93	$213.95	$213.90
Purchase #2	$23.72	9.815%	$26.0481	$26.05	$26.05	$26.00
Purchase #3	$18.43	7.761%	$19.8604	$19.86	$19.85	$19.90
Purchase #4	$34.83	8.630%	$37.8358	$37.84	$37.85	$37.80
Purchase #5	$156.91	7.565%	$168.7802	$168.78	$168.80	$168.80
Purchase #6	$196.27	7.874%	$211.7243	$211.72	$211.70	$211.70
Purchase #7	$29.59	9.402%	$32.3721	$32.37	$32.35	$32.40
7 purchase totals =	$666.39		$710.5553	$710.55	$710.55	$710.50