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	$68.57	6.354%	$72.9269	$72.93	$72.95	$72.90
Purchase #2	$109.58	11.533%	$122.2179	$122.22	$122.20	$122.20
Purchase #3	$72.75	6.187%	$77.251	$77.25	$77.25	$77.30
Purchase #4	$158.94	4.382%	$165.9048	$165.90	$165.90	$165.90
Purchase #5	$192.42	11.842%	$215.2064	$215.21	$215.20	$215.20
Purchase #6	$169.37	5.834%	$179.251	$179.25	$179.25	$179.30
Purchase #7	$244.58	7.382%	$262.6349	$262.63	$262.65	$262.60
7 purchase totals =	$1,016.21		$1,095.3929	$1,095.39	$1,095.40	$1,095.40