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	$93.98	8.493%	$101.9617	$101.96	$101.95	$102.00
Purchase #2	$52.38	13.796%	$59.6063	$59.61	$59.60	$59.60
Purchase #3	$47.50	8.189%	$51.3898	$51.39	$51.40	$51.40
Purchase #4	$75.70	8.480%	$82.1194	$82.12	$82.10	$82.10
Purchase #5	$37.39	11.670%	$41.7534	$41.75	$41.75	$41.80
Purchase #6	$6.96	9.200%	$7.6003	$7.60	$7.60	$7.60
Purchase #7	$147.43	4.425%	$153.9538	$153.95	$153.95	$154.00
7 purchase totals =	$461.34		$498.3847	$498.38	$498.35	$498.50