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	$167.37	8.460%	$181.5295	$181.53	$181.55	$181.50
Purchase #2	$167.92	5.136%	$176.5444	$176.54	$176.55	$176.50
Purchase #3	$86.81	9.870%	$95.3781	$95.38	$95.40	$95.40
Purchase #4	$105.27	6.844%	$112.4747	$112.47	$112.45	$112.50
Purchase #5	$97.45	13.367%	$110.4761	$110.48	$110.50	$110.50
Purchase #6	$137.61	11.397%	$153.2934	$153.29	$153.30	$153.30
Purchase #7	$174.67	8.567%	$189.634	$189.63	$189.65	$189.60
7 purchase totals =	$937.10		$1,019.3302	$1,019.32	$1,019.40	$1,019.30