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	$157.98	9.858%	$173.5537	$173.55	$173.55	$173.60
Purchase #2	$245.79	4.371%	$256.5335	$256.53	$256.55	$256.50
Purchase #3	$131.88	3.248%	$136.1635	$136.16	$136.15	$136.20
Purchase #4	$239.77	13.515%	$272.1749	$272.17	$272.15	$272.20
Purchase #5	$23.63	5.515%	$24.9332	$24.93	$24.95	$24.90
Purchase #6	$161.61	5.810%	$170.9995	$171.00	$171.00	$171.00
Purchase #7	$152.34	6.374%	$162.0502	$162.05	$162.05	$162.10
7 purchase totals =	$1,113.00		$1,196.4085	$1,196.39	$1,196.40	$1,196.50