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	$137.65	10.832%	$152.5602	$152.56	$152.55	$152.60
Purchase #2	$59.50	6.869%	$63.5871	$63.59	$63.60	$63.60
Purchase #3	$93.79	8.648%	$101.901	$101.90	$101.90	$101.90
Purchase #4	$102.40	8.853%	$111.4655	$111.47	$111.45	$111.50
Purchase #5	$85.42	8.390%	$92.5867	$92.59	$92.60	$92.60
Purchase #6	$234.51	12.762%	$264.4382	$264.44	$264.45	$264.40
Purchase #7	$197.64	10.412%	$218.2183	$218.22	$218.20	$218.20
7 purchase totals =	$910.91		$1,004.7570	$1,004.77	$1,004.75	$1,004.80