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	$85.27	11.545%	$95.1144	$95.11	$95.10	$95.10
Purchase #2	$237.94	9.224%	$259.8876	$259.89	$259.90	$259.90
Purchase #3	$176.35	11.198%	$196.0977	$196.10	$196.10	$196.10
Purchase #4	$55.57	6.142%	$58.9831	$58.98	$59.00	$59.00
Purchase #5	$171.26	10.840%	$189.8246	$189.82	$189.80	$189.80
Purchase #6	$94.51	6.828%	$100.9631	$100.96	$100.95	$101.00
Purchase #7	$135.97	4.565%	$142.177	$142.18	$142.20	$142.20
7 purchase totals =	$956.87		$1,043.0475	$1,043.04	$1,043.05	$1,043.10