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	$69.55	3.534%	$72.0079	$72.01	$72.00	$72.00
Purchase #2	$74.60	7.858%	$80.4621	$80.46	$80.45	$80.50
Purchase #3	$85.28	5.619%	$90.0719	$90.07	$90.05	$90.10
Purchase #4	$190.75	7.840%	$205.7048	$205.70	$205.70	$205.70
Purchase #5	$168.92	8.608%	$183.4606	$183.46	$183.45	$183.50
Purchase #6	$231.47	8.400%	$250.9135	$250.91	$250.90	$250.90
Purchase #7	$188.27	7.799%	$202.9532	$202.95	$202.95	$203.00
7 purchase totals =	$1,008.84		$1,085.5740	$1,085.56	$1,085.50	$1,085.70