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	$198.32	10.710%	$219.5601	$219.56	$219.55	$219.60
Purchase #2	$33.69	11.377%	$37.5229	$37.52	$37.50	$37.50
Purchase #3	$154.57	11.586%	$172.4785	$172.48	$172.50	$172.50
Purchase #4	$192.75	11.807%	$215.508	$215.51	$215.50	$215.50
Purchase #5	$146.35	10.330%	$161.468	$161.47	$161.45	$161.50
Purchase #6	$53.70	11.869%	$60.0737	$60.07	$60.05	$60.10
Purchase #7	$173.71	7.591%	$186.8963	$186.90	$186.90	$186.90
7 purchase totals =	$953.09		$1,053.5075	$1,053.51	$1,053.45	$1,053.60