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	$246.89	3.297%	$255.03	$255.03	$255.05	$255.00
Purchase #2	$40.54	3.361%	$41.9025	$41.90	$41.90	$41.90
Purchase #3	$104.51	13.152%	$118.2552	$118.26	$118.25	$118.30
Purchase #4	$181.34	8.763%	$197.2308	$197.23	$197.25	$197.20
Purchase #5	$218.75	6.688%	$233.38	$233.38	$233.40	$233.40
Purchase #6	$147.78	7.777%	$159.2729	$159.27	$159.25	$159.30
Purchase #7	$77.46	12.294%	$86.9829	$86.98	$87.00	$87.00
7 purchase totals =	$1,017.27		$1,092.0543	$1,092.05	$1,092.10	$1,092.10