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	$214.93	9.853%	$236.1071	$236.11	$236.10	$236.10
Purchase #2	$45.54	3.189%	$46.9923	$46.99	$47.00	$47.00
Purchase #3	$127.89	7.570%	$137.5713	$137.57	$137.55	$137.60
Purchase #4	$218.59	5.738%	$231.1327	$231.13	$231.15	$231.10
Purchase #5	$156.40	11.694%	$174.6894	$174.69	$174.70	$174.70
Purchase #6	$19.41	12.705%	$21.876	$21.88	$21.90	$21.90
Purchase #7	$147.46	10.168%	$162.4537	$162.45	$162.45	$162.50
7 purchase totals =	$930.22		$1,010.8225	$1,010.82	$1,010.85	$1,010.90