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	$157.86	8.821%	$171.7848	$171.78	$171.80	$171.80
Purchase #2	$44.60	13.527%	$50.633	$50.63	$50.65	$50.60
Purchase #3	$153.77	5.763%	$162.6318	$162.63	$162.65	$162.60
Purchase #4	$60.41	3.756%	$62.679	$62.68	$62.70	$62.70
Purchase #5	$170.51	11.157%	$189.5338	$189.53	$189.55	$189.50
Purchase #6	$232.69	3.524%	$240.89	$240.89	$240.90	$240.90
Purchase #7	$130.55	12.616%	$147.0202	$147.02	$147.00	$147.00
7 purchase totals =	$950.39		$1,025.1726	$1,025.16	$1,025.25	$1,025.10