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	$68.70	4.751%	$71.9639	$71.96	$71.95	$72.00
Purchase #2	$189.25	9.295%	$206.8408	$206.84	$206.85	$206.80
Purchase #3	$182.64	4.733%	$191.2844	$191.28	$191.30	$191.30
Purchase #4	$133.38	4.226%	$139.0166	$139.02	$139.00	$139.00
Purchase #5	$56.27	5.671%	$59.4611	$59.46	$59.45	$59.50
Purchase #6	$192.87	3.176%	$198.9956	$199.00	$199.00	$199.00
Purchase #7	$130.75	10.427%	$144.3833	$144.38	$144.40	$144.40
7 purchase totals =	$953.86		$1,011.9457	$1,011.94	$1,011.95	$1,012.00