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	$177.38	8.176%	$191.8826	$191.88	$191.90	$191.90
Purchase #2	$97.28	8.599%	$105.6451	$105.65	$105.65	$105.60
Purchase #3	$145.35	4.827%	$152.366	$152.37	$152.35	$152.40
Purchase #4	$98.97	6.732%	$105.6327	$105.63	$105.65	$105.60
Purchase #5	$163.86	13.179%	$185.4551	$185.46	$185.45	$185.50
Purchase #6	$179.69	7.691%	$193.51	$193.51	$193.50	$193.50
Purchase #7	$108.90	9.834%	$119.6092	$119.61	$119.60	$119.60
7 purchase totals =	$971.43		$1,054.1007	$1,054.11	$1,054.10	$1,054.10