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	$184.55	6.593%	$196.7174	$196.72	$196.70	$196.70
Purchase #2	$142.28	11.400%	$158.4999	$158.50	$158.50	$158.50
Purchase #3	$168.34	9.871%	$184.9568	$184.96	$184.95	$185.00
Purchase #4	$229.80	4.511%	$240.1663	$240.17	$240.15	$240.20
Purchase #5	$90.36	4.442%	$94.3738	$94.37	$94.35	$94.40
Purchase #6	$185.46	8.206%	$200.6788	$200.68	$200.70	$200.70
Purchase #7	$86.52	9.186%	$94.4677	$94.47	$94.45	$94.50
7 purchase totals =	$1,087.31		$1,169.8607	$1,169.87	$1,169.80	$1,170.00