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	$194.65	7.225%	$208.7135	$208.71	$208.70	$208.70
Purchase #2	$168.45	10.377%	$185.9301	$185.93	$185.95	$185.90
Purchase #3	$70.63	6.635%	$75.3163	$75.32	$75.30	$75.30
Purchase #4	$101.74	9.134%	$111.0329	$111.03	$111.05	$111.00
Purchase #5	$229.47	12.227%	$257.5273	$257.53	$257.55	$257.50
Purchase #6	$133.39	10.826%	$147.8308	$147.83	$147.85	$147.80
Purchase #7	$42.42	3.564%	$43.9318	$43.93	$43.95	$43.90
7 purchase totals =	$940.75		$1,030.2827	$1,030.28	$1,030.35	$1,030.10