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	$103.66	13.674%	$117.8345	$117.83	$117.85	$117.80
Purchase #2	$174.63	13.492%	$198.1911	$198.19	$198.20	$198.20
Purchase #3	$88.66	13.322%	$100.4713	$100.47	$100.45	$100.50
Purchase #4	$226.73	9.228%	$247.6526	$247.65	$247.65	$247.70
Purchase #5	$120.64	9.363%	$131.9355	$131.94	$131.95	$131.90
Purchase #6	$50.96	7.459%	$54.7611	$54.76	$54.75	$54.80
Purchase #7	$159.34	9.346%	$174.2319	$174.23	$174.25	$174.20
7 purchase totals =	$924.62		$1,025.0780	$1,025.07	$1,025.10	$1,025.10