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	$99.46	6.512%	$105.9368	$105.94	$105.95	$105.90
Purchase #2	$131.98	3.799%	$136.9939	$136.99	$137.00	$137.00
Purchase #3	$181.30	12.677%	$204.2834	$204.28	$204.30	$204.30
Purchase #4	$12.38	8.706%	$13.4578	$13.46	$13.45	$13.50
Purchase #5	$195.36	13.199%	$221.1456	$221.15	$221.15	$221.10
Purchase #6	$199.68	8.435%	$216.523	$216.52	$216.50	$216.50
Purchase #7	$173.52	13.435%	$196.8324	$196.83	$196.85	$196.80
7 purchase totals =	$993.68		$1,095.1729	$1,095.17	$1,095.20	$1,095.10