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	$182.57	7.510%	$196.281	$196.28	$196.30	$196.30
Purchase #2	$228.32	9.393%	$249.7661	$249.77	$249.75	$249.80
Purchase #3	$131.87	9.364%	$144.2183	$144.22	$144.20	$144.20
Purchase #4	$202.44	11.621%	$225.9656	$225.97	$225.95	$226.00
Purchase #5	$179.45	13.863%	$204.3272	$204.33	$204.35	$204.30
Purchase #6	$141.41	9.534%	$154.892	$154.89	$154.90	$154.90
Purchase #7	$33.33	11.723%	$37.2373	$37.24	$37.25	$37.20
7 purchase totals =	$1,099.39		$1,212.6875	$1,212.70	$1,212.70	$1,212.70