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	$168.54	10.215%	$185.7564	$185.76	$185.75	$185.80
Purchase #2	$196.64	13.699%	$223.5777	$223.58	$223.60	$223.60
Purchase #3	$237.91	10.603%	$263.1356	$263.14	$263.15	$263.10
Purchase #4	$51.56	8.833%	$56.1143	$56.11	$56.10	$56.10
Purchase #5	$179.67	11.143%	$199.6906	$199.69	$199.70	$199.70
Purchase #6	$149.85	3.768%	$155.4963	$155.50	$155.50	$155.50
Purchase #7	$166.75	7.205%	$178.7643	$178.76	$178.75	$178.80
7 purchase totals =	$1,150.92		$1,262.5352	$1,262.54	$1,262.55	$1,262.60