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	$189.50	3.720%	$196.5494	$196.55	$196.55	$196.50
Purchase #2	$45.87	3.106%	$47.2947	$47.29	$47.30	$47.30
Purchase #3	$49.61	10.398%	$54.7684	$54.77	$54.75	$54.80
Purchase #4	$175.68	12.840%	$198.2373	$198.24	$198.25	$198.20
Purchase #5	$238.86	3.289%	$246.7161	$246.72	$246.70	$246.70
Purchase #6	$179.35	3.416%	$185.4766	$185.48	$185.50	$185.50
Purchase #7	$91.62	11.634%	$102.2791	$102.28	$102.30	$102.30
7 purchase totals =	$970.49		$1,031.3216	$1,031.33	$1,031.35	$1,031.30