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	$235.69	13.357%	$267.1711	$267.17	$267.15	$267.20
Purchase #2	$73.69	12.625%	$82.9934	$82.99	$83.00	$83.00
Purchase #3	$40.36	6.446%	$42.9616	$42.96	$42.95	$43.00
Purchase #4	$224.88	5.814%	$237.9545	$237.95	$237.95	$238.00
Purchase #5	$136.96	10.125%	$150.8272	$150.83	$150.85	$150.80
Purchase #6	$36.61	10.363%	$40.4039	$40.40	$40.40	$40.40
Purchase #7	$187.67	3.484%	$194.2084	$194.21	$194.20	$194.20
7 purchase totals =	$935.86		$1,016.5201	$1,016.51	$1,016.50	$1,016.60