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	$95.32	4.280%	$99.3997	$99.40	$99.40	$99.40
Purchase #2	$213.90	7.317%	$229.5511	$229.55	$229.55	$229.60
Purchase #3	$169.91	3.689%	$176.178	$176.18	$176.20	$176.20
Purchase #4	$31.39	6.650%	$33.4774	$33.48	$33.50	$33.50
Purchase #5	$42.45	7.795%	$45.759	$45.76	$45.75	$45.80
Purchase #6	$172.89	4.832%	$181.244	$181.24	$181.25	$181.20
Purchase #7	$185.71	12.703%	$209.3007	$209.30	$209.30	$209.30
7 purchase totals =	$911.57		$974.9099	$974.91	$974.95	$975.00