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	$173.52	13.329%	$196.6485	$196.65	$196.65	$196.60
Purchase #2	$204.44	3.864%	$212.3396	$212.34	$212.35	$212.30
Purchase #3	$211.43	7.594%	$227.486	$227.49	$227.50	$227.50
Purchase #4	$92.61	11.147%	$102.9332	$102.93	$102.95	$102.90
Purchase #5	$88.81	3.507%	$91.9246	$91.92	$91.90	$91.90
Purchase #6	$123.41	12.816%	$139.2262	$139.23	$139.25	$139.20
Purchase #7	$208.75	8.122%	$225.7047	$225.70	$225.70	$225.70
7 purchase totals =	$1,102.97		$1,196.2628	$1,196.26	$1,196.30	$1,196.10