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	$177.74	10.281%	$196.0134	$196.01	$196.00	$196.00
Purchase #2	$208.60	10.266%	$230.0149	$230.01	$230.00	$230.00
Purchase #3	$74.35	9.134%	$81.1411	$81.14	$81.15	$81.10
Purchase #4	$36.27	10.508%	$40.0813	$40.08	$40.10	$40.10
Purchase #5	$80.41	3.665%	$83.357	$83.36	$83.35	$83.40
Purchase #6	$115.56	9.140%	$126.1222	$126.12	$126.10	$126.10
Purchase #7	$196.50	11.712%	$219.5141	$219.51	$219.50	$219.50
7 purchase totals =	$889.43		$976.2440	$976.23	$976.20	$976.20