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	$107.64	3.130%	$111.0091	$111.01	$111.00	$111.00
Purchase #2	$192.48	13.368%	$218.2107	$218.21	$218.20	$218.20
Purchase #3	$63.42	12.827%	$71.5549	$71.55	$71.55	$71.60
Purchase #4	$103.93	7.684%	$111.916	$111.92	$111.90	$111.90
Purchase #5	$124.73	5.343%	$131.3943	$131.39	$131.40	$131.40
Purchase #6	$187.87	3.495%	$194.4361	$194.44	$194.45	$194.40
Purchase #7	$202.34	8.727%	$219.9982	$220.00	$220.00	$220.00
7 purchase totals =	$982.41		$1,058.5193	$1,058.52	$1,058.50	$1,058.50