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	$95.56	9.532%	$104.6688	$104.67	$104.65	$104.70
Purchase #2	$168.50	13.667%	$191.5289	$191.53	$191.55	$191.50
Purchase #3	$152.34	10.705%	$168.648	$168.65	$168.65	$168.60
Purchase #4	$240.91	6.268%	$256.0102	$256.01	$256.00	$256.00
Purchase #5	$36.34	7.666%	$39.1258	$39.13	$39.15	$39.10
Purchase #6	$66.46	4.696%	$69.581	$69.58	$69.60	$69.60
Purchase #7	$213.74	5.379%	$225.2371	$225.24	$225.25	$225.20
7 purchase totals =	$973.85		$1,054.7998	$1,054.81	$1,054.85	$1,054.70