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	$173.81	13.184%	$196.7251	$196.73	$196.75	$196.70
Purchase #2	$227.55	13.624%	$258.5514	$258.55	$258.55	$258.60
Purchase #3	$142.58	7.240%	$152.9028	$152.90	$152.90	$152.90
Purchase #4	$101.78	7.636%	$109.5519	$109.55	$109.55	$109.60
Purchase #5	$99.54	7.124%	$106.6312	$106.63	$106.65	$106.60
Purchase #6	$122.47	9.843%	$134.5247	$134.52	$134.50	$134.50
Purchase #7	$137.91	11.267%	$153.4483	$153.45	$153.45	$153.40
7 purchase totals =	$1,005.64		$1,112.3354	$1,112.33	$1,112.35	$1,112.30