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	$168.79	11.729%	$188.5874	$188.59	$188.60	$188.60
Purchase #2	$191.85	12.823%	$216.4509	$216.45	$216.45	$216.50
Purchase #3	$212.76	6.605%	$226.8128	$226.81	$226.80	$226.80
Purchase #4	$147.60	5.757%	$156.0973	$156.10	$156.10	$156.10
Purchase #5	$143.29	12.612%	$161.3617	$161.36	$161.35	$161.40
Purchase #6	$54.57	8.147%	$59.0158	$59.02	$59.00	$59.00
Purchase #7	$48.92	3.166%	$50.4688	$50.47	$50.45	$50.50
7 purchase totals =	$967.78		$1,058.7947	$1,058.80	$1,058.75	$1,058.90