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	$46.48	5.313%	$48.9495	$48.95	$48.95	$48.90
Purchase #2	$69.85	11.357%	$77.7829	$77.78	$77.80	$77.80
Purchase #3	$176.61	4.505%	$184.5663	$184.57	$184.55	$184.60
Purchase #4	$59.67	4.282%	$62.2251	$62.23	$62.25	$62.20
Purchase #5	$157.77	9.604%	$172.9222	$172.92	$172.90	$172.90
Purchase #6	$84.40	6.849%	$90.1806	$90.18	$90.20	$90.20
Purchase #7	$156.42	3.862%	$162.4609	$162.46	$162.45	$162.50
7 purchase totals =	$751.20		$799.0875	$799.09	$799.10	$799.10