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	$233.69	4.590%	$244.4164	$244.42	$244.40	$244.40
Purchase #2	$190.96	12.655%	$215.126	$215.13	$215.15	$215.10
Purchase #3	$172.41	12.806%	$194.4888	$194.49	$194.50	$194.50
Purchase #4	$126.41	3.640%	$131.0113	$131.01	$131.00	$131.00
Purchase #5	$147.64	13.577%	$167.6851	$167.69	$167.70	$167.70
Purchase #6	$22.89	7.221%	$24.5429	$24.54	$24.55	$24.50
Purchase #7	$54.40	4.646%	$56.9274	$56.93	$56.95	$56.90
7 purchase totals =	$948.40		$1,034.1979	$1,034.21	$1,034.25	$1,034.10