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	$194.40	8.390%	$210.7102	$210.71	$210.70	$210.70
Purchase #2	$147.43	7.745%	$158.8485	$158.85	$158.85	$158.80
Purchase #3	$197.55	12.205%	$221.661	$221.66	$221.65	$221.70
Purchase #4	$134.28	4.847%	$140.7886	$140.79	$140.80	$140.80
Purchase #5	$208.89	12.658%	$235.3313	$235.33	$235.35	$235.30
Purchase #6	$98.66	7.244%	$105.8069	$105.81	$105.80	$105.80
Purchase #7	$141.68	6.142%	$150.382	$150.38	$150.40	$150.40
7 purchase totals =	$1,122.89		$1,223.5285	$1,223.53	$1,223.55	$1,223.50