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	$165.64	12.821%	$186.8767	$186.88	$186.90	$186.90
Purchase #2	$59.33	4.389%	$61.934	$61.93	$61.95	$61.90
Purchase #3	$85.40	11.148%	$94.9204	$94.92	$94.90	$94.90
Purchase #4	$200.99	11.164%	$223.4285	$223.43	$223.45	$223.40
Purchase #5	$105.41	3.404%	$108.9982	$109.00	$109.00	$109.00
Purchase #6	$231.48	3.483%	$239.5424	$239.54	$239.55	$239.50
Purchase #7	$146.32	4.265%	$152.5605	$152.56	$152.55	$152.60
7 purchase totals =	$994.57		$1,068.2607	$1,068.26	$1,068.30	$1,068.20