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	$83.83	4.298%	$87.433	$87.43	$87.45	$87.40
Purchase #2	$233.26	4.267%	$243.2132	$243.21	$243.20	$243.20
Purchase #3	$217.76	3.303%	$224.9526	$224.95	$224.95	$225.00
Purchase #4	$69.81	12.448%	$78.4999	$78.50	$78.50	$78.50
Purchase #5	$61.31	10.117%	$67.5127	$67.51	$67.50	$67.50
Purchase #6	$81.76	6.690%	$87.2297	$87.23	$87.25	$87.20
Purchase #7	$200.46	7.681%	$215.8573	$215.86	$215.85	$215.90
7 purchase totals =	$948.19		$1,004.6984	$1,004.69	$1,004.70	$1,004.70