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	$143.66	6.323%	$152.7436	$152.74	$152.75	$152.70
Purchase #2	$95.34	5.742%	$100.8144	$100.81	$100.80	$100.80
Purchase #3	$169.28	7.334%	$181.695	$181.70	$181.70	$181.70
Purchase #4	$196.28	10.485%	$216.86	$216.86	$216.85	$216.90
Purchase #5	$52.52	8.542%	$57.0063	$57.01	$57.00	$57.00
Purchase #6	$131.87	13.266%	$149.3639	$149.36	$149.35	$149.40
Purchase #7	$152.37	5.583%	$160.8768	$160.88	$160.90	$160.90
7 purchase totals =	$941.32		$1,019.3600	$1,019.36	$1,019.35	$1,019.40