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	$130.89	5.377%	$137.928	$137.93	$137.95	$137.90
Purchase #2	$130.90	6.415%	$139.2972	$139.30	$139.30	$139.30
Purchase #3	$179.56	6.668%	$191.5331	$191.53	$191.55	$191.50
Purchase #4	$65.42	3.208%	$67.5187	$67.52	$67.50	$67.50
Purchase #5	$157.84	9.812%	$173.3273	$173.33	$173.35	$173.30
Purchase #6	$136.71	5.644%	$144.4259	$144.43	$144.45	$144.40
Purchase #7	$194.34	5.701%	$205.4193	$205.42	$205.40	$205.40
7 purchase totals =	$995.66		$1,059.4495	$1,059.46	$1,059.50	$1,059.30