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	$196.35	10.477%	$216.9216	$216.92	$216.90	$216.90
Purchase #2	$217.72	10.843%	$241.3274	$241.33	$241.35	$241.30
Purchase #3	$54.73	8.648%	$59.4631	$59.46	$59.45	$59.50
Purchase #4	$19.73	10.289%	$21.76	$21.76	$21.75	$21.80
Purchase #5	$36.49	3.303%	$37.6953	$37.70	$37.70	$37.70
Purchase #6	$78.35	12.776%	$88.36	$88.36	$88.35	$88.40
Purchase #7	$103.86	12.544%	$116.8882	$116.89	$116.90	$116.90
7 purchase totals =	$707.23		$782.4156	$782.42	$782.40	$782.50