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	$92.66	7.276%	$99.4019	$99.40	$99.40	$99.40
Purchase #2	$201.89	13.674%	$229.4964	$229.50	$229.50	$229.50
Purchase #3	$165.99	4.803%	$173.9625	$173.96	$173.95	$174.00
Purchase #4	$14.42	10.392%	$15.9185	$15.92	$15.90	$15.90
Purchase #5	$158.33	6.712%	$168.9571	$168.96	$168.95	$169.00
Purchase #6	$241.56	10.298%	$266.4358	$266.44	$266.45	$266.40
Purchase #7	$136.85	3.494%	$141.6315	$141.63	$141.65	$141.60
7 purchase totals =	$1,011.70		$1,095.8037	$1,095.81	$1,095.80	$1,095.80