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	$145.75	10.471%	$161.0115	$161.01	$161.00	$161.00
Purchase #2	$120.56	13.186%	$136.457	$136.46	$136.45	$136.50
Purchase #3	$216.36	12.524%	$243.4569	$243.46	$243.45	$243.50
Purchase #4	$102.36	11.325%	$113.9523	$113.95	$113.95	$114.00
Purchase #5	$181.29	8.398%	$196.5147	$196.51	$196.50	$196.50
Purchase #6	$54.26	8.732%	$58.998	$59.00	$59.00	$59.00
Purchase #7	$244.40	4.480%	$255.3491	$255.35	$255.35	$255.30
7 purchase totals =	$1,064.98		$1,165.7395	$1,165.74	$1,165.70	$1,165.80