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	$187.34	10.469%	$206.9526	$206.95	$206.95	$207.00
Purchase #2	$12.79	13.710%	$14.5435	$14.54	$14.55	$14.50
Purchase #3	$129.37	10.457%	$142.8982	$142.90	$142.90	$142.90
Purchase #4	$107.42	11.761%	$120.0537	$120.05	$120.05	$120.10
Purchase #5	$53.67	10.816%	$59.4749	$59.47	$59.45	$59.50
Purchase #6	$120.86	13.661%	$137.3707	$137.37	$137.35	$137.40
Purchase #7	$209.73	5.584%	$221.4413	$221.44	$221.45	$221.40
7 purchase totals =	$821.18		$902.7349	$902.72	$902.70	$902.80