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	$172.92	11.359%	$192.562	$192.56	$192.55	$192.60
Purchase #2	$13.38	11.721%	$14.9483	$14.95	$14.95	$14.90
Purchase #3	$55.74	3.863%	$57.8932	$57.89	$57.90	$57.90
Purchase #4	$22.36	8.510%	$24.2628	$24.26	$24.25	$24.30
Purchase #5	$154.41	11.509%	$172.181	$172.18	$172.20	$172.20
Purchase #6	$141.39	6.167%	$150.1095	$150.11	$150.10	$150.10
Purchase #7	$91.37	8.804%	$99.4142	$99.41	$99.40	$99.40
7 purchase totals =	$651.57		$711.3710	$711.36	$711.35	$711.40