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	$146.31	4.139%	$152.3658	$152.37	$152.35	$152.40
Purchase #2	$8.56	4.316%	$8.9294	$8.93	$8.95	$8.90
Purchase #3	$105.40	5.622%	$111.3256	$111.33	$111.35	$111.30
Purchase #4	$153.36	6.157%	$162.8024	$162.80	$162.80	$162.80
Purchase #5	$244.27	11.267%	$271.7919	$271.79	$271.80	$271.80
Purchase #6	$152.80	7.858%	$164.807	$164.81	$164.80	$164.80
Purchase #7	$201.88	7.599%	$217.2209	$217.22	$217.20	$217.20
7 purchase totals =	$1,012.58		$1,089.2430	$1,089.25	$1,089.25	$1,089.20