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	$90.61	5.377%	$95.4821	$95.48	$95.50	$95.50
Purchase #2	$166.54	11.716%	$186.0518	$186.05	$186.05	$186.10
Purchase #3	$168.99	8.607%	$183.535	$183.54	$183.55	$183.50
Purchase #4	$214.80	3.627%	$222.5908	$222.59	$222.60	$222.60
Purchase #5	$81.31	8.393%	$88.1343	$88.13	$88.15	$88.10
Purchase #6	$104.85	9.468%	$114.7772	$114.78	$114.80	$114.80
Purchase #7	$190.73	3.160%	$196.7571	$196.76	$196.75	$196.80
7 purchase totals =	$1,017.83		$1,087.3283	$1,087.33	$1,087.40	$1,087.40