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	$87.59	5.325%	$92.2542	$92.25	$92.25	$92.30
Purchase #2	$219.78	5.661%	$232.2217	$232.22	$232.20	$232.20
Purchase #3	$85.86	5.278%	$90.3917	$90.39	$90.40	$90.40
Purchase #4	$34.94	5.456%	$36.8463	$36.85	$36.85	$36.80
Purchase #5	$43.61	9.300%	$47.6657	$47.67	$47.65	$47.70
Purchase #6	$123.38	3.372%	$127.5404	$127.54	$127.55	$127.50
Purchase #7	$197.43	9.526%	$216.2372	$216.24	$216.25	$216.20
7 purchase totals =	$792.59		$843.1572	$843.16	$843.15	$843.10