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	$168.96	7.497%	$181.6269	$181.63	$181.65	$181.60
Purchase #2	$162.95	11.337%	$181.4236	$181.42	$181.40	$181.40
Purchase #3	$42.34	6.461%	$45.0756	$45.08	$45.10	$45.10
Purchase #4	$223.78	4.871%	$234.6803	$234.68	$234.70	$234.70
Purchase #5	$141.97	7.679%	$152.8719	$152.87	$152.85	$152.90
Purchase #6	$84.39	13.429%	$95.7227	$95.72	$95.70	$95.70
Purchase #7	$109.31	3.260%	$112.8735	$112.87	$112.85	$112.90
7 purchase totals =	$933.70		$1,004.2745	$1,004.27	$1,004.25	$1,004.30