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	$90.75	13.433%	$102.9404	$102.94	$102.95	$102.90
Purchase #2	$47.86	13.619%	$54.3781	$54.38	$54.40	$54.40
Purchase #3	$6.73	7.674%	$7.2465	$7.25	$7.25	$7.20
Purchase #4	$210.35	4.533%	$219.8852	$219.89	$219.90	$219.90
Purchase #5	$170.56	8.258%	$184.6448	$184.64	$184.65	$184.60
Purchase #6	$112.53	11.612%	$125.597	$125.60	$125.60	$125.60
Purchase #7	$61.56	9.480%	$67.3959	$67.40	$67.40	$67.40
7 purchase totals =	$700.34		$762.0879	$762.10	$762.15	$762.00