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	$187.43	4.590%	$196.033	$196.03	$196.05	$196.00
Purchase #2	$56.45	9.757%	$61.9578	$61.96	$61.95	$62.00
Purchase #3	$107.47	10.415%	$118.663	$118.66	$118.65	$118.70
Purchase #4	$30.48	5.388%	$32.1223	$32.12	$32.10	$32.10
Purchase #5	$188.32	13.245%	$213.263	$213.26	$213.25	$213.30
Purchase #6	$204.55	10.264%	$225.545	$225.55	$225.55	$225.50
Purchase #7	$168.53	8.324%	$182.5584	$182.56	$182.55	$182.60
7 purchase totals =	$943.23		$1,030.1425	$1,030.14	$1,030.10	$1,030.20