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	$85.51	11.126%	$95.0238	$95.02	$95.00	$95.00
Purchase #2	$42.82	5.801%	$45.304	$45.30	$45.30	$45.30
Purchase #3	$159.62	12.399%	$179.4113	$179.41	$179.40	$179.40
Purchase #4	$24.87	12.807%	$28.0551	$28.06	$28.05	$28.10
Purchase #5	$223.84	3.695%	$232.1109	$232.11	$232.10	$232.10
Purchase #6	$97.78	8.287%	$105.883	$105.88	$105.90	$105.90
Purchase #7	$86.84	6.764%	$92.7139	$92.71	$92.70	$92.70
7 purchase totals =	$721.28		$778.5020	$778.49	$778.45	$778.50