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	$96.31	10.315%	$106.2444	$106.24	$106.25	$106.20
Purchase #2	$13.51	5.177%	$14.2094	$14.21	$14.20	$14.20
Purchase #3	$48.57	3.157%	$50.1034	$50.10	$50.10	$50.10
Purchase #4	$115.93	7.449%	$124.5656	$124.57	$124.55	$124.60
Purchase #5	$96.76	4.181%	$100.8055	$100.81	$100.80	$100.80
Purchase #6	$160.26	7.791%	$172.7459	$172.75	$172.75	$172.70
Purchase #7	$173.55	6.790%	$185.334	$185.33	$185.35	$185.30
7 purchase totals =	$704.89		$754.0082	$754.01	$754.00	$753.90