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	$115.56	8.680%	$125.5906	$125.59	$125.60	$125.60
Purchase #2	$130.97	4.714%	$137.1439	$137.14	$137.15	$137.10
Purchase #3	$244.50	5.754%	$258.5685	$258.57	$258.55	$258.60
Purchase #4	$110.89	6.666%	$118.2819	$118.28	$118.30	$118.30
Purchase #5	$153.65	4.397%	$160.406	$160.41	$160.40	$160.40
Purchase #6	$174.37	4.715%	$182.5915	$182.59	$182.60	$182.60
Purchase #7	$104.71	6.591%	$111.6114	$111.61	$111.60	$111.60
7 purchase totals =	$1,034.65		$1,094.1938	$1,094.19	$1,094.20	$1,094.20