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	$107.42	5.495%	$113.3227	$113.32	$113.30	$113.30
Purchase #2	$112.79	4.540%	$117.9107	$117.91	$117.90	$117.90
Purchase #3	$14.55	9.119%	$15.8768	$15.88	$15.90	$15.90
Purchase #4	$104.81	6.656%	$111.7862	$111.79	$111.80	$111.80
Purchase #5	$117.34	6.171%	$124.5811	$124.58	$124.60	$124.60
Purchase #6	$107.82	4.744%	$112.935	$112.94	$112.95	$112.90
Purchase #7	$196.73	7.749%	$211.9746	$211.97	$211.95	$212.00
7 purchase totals =	$761.46		$808.3871	$808.39	$808.40	$808.40