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	$87.78	8.269%	$95.0385	$95.04	$95.05	$95.00
Purchase #2	$173.44	3.360%	$179.2676	$179.27	$179.25	$179.30
Purchase #3	$169.52	5.192%	$178.3215	$178.32	$178.30	$178.30
Purchase #4	$86.89	8.736%	$94.4807	$94.48	$94.50	$94.50
Purchase #5	$72.49	8.609%	$78.7307	$78.73	$78.75	$78.70
Purchase #6	$7.29	6.478%	$7.7622	$7.76	$7.75	$7.80
Purchase #7	$64.55	9.435%	$70.6403	$70.64	$70.65	$70.60
7 purchase totals =	$661.96		$704.2415	$704.24	$704.25	$704.20