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	$58.88	5.183%	$61.9318	$61.93	$61.95	$61.90
Purchase #2	$76.97	11.588%	$85.8893	$85.89	$85.90	$85.90
Purchase #3	$245.72	4.316%	$256.3253	$256.33	$256.35	$256.30
Purchase #4	$218.93	12.272%	$245.7971	$245.80	$245.80	$245.80
Purchase #5	$184.48	3.281%	$190.5328	$190.53	$190.55	$190.50
Purchase #6	$156.59	6.396%	$166.6055	$166.61	$166.60	$166.60
Purchase #7	$134.61	7.248%	$144.3665	$144.37	$144.35	$144.40
7 purchase totals =	$1,076.18		$1,151.4483	$1,151.46	$1,151.50	$1,151.40