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	$194.81	12.441%	$219.0463	$219.05	$219.05	$219.00
Purchase #2	$187.51	10.699%	$207.5717	$207.57	$207.55	$207.60
Purchase #3	$212.85	5.651%	$224.8782	$224.88	$224.90	$224.90
Purchase #4	$169.25	13.193%	$191.5792	$191.58	$191.60	$191.60
Purchase #5	$52.60	13.483%	$59.6921	$59.69	$59.70	$59.70
Purchase #6	$99.87	13.732%	$113.5841	$113.58	$113.60	$113.60
Purchase #7	$33.56	12.620%	$37.7953	$37.80	$37.80	$37.80
7 purchase totals =	$950.45		$1,054.1469	$1,054.15	$1,054.20	$1,054.20