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	$219.29	6.313%	$233.1338	$233.13	$233.15	$233.10
Purchase #2	$86.58	3.266%	$89.4077	$89.41	$89.40	$89.40
Purchase #3	$175.29	9.537%	$192.0074	$192.01	$192.00	$192.00
Purchase #4	$54.69	11.259%	$60.8475	$60.85	$60.85	$60.80
Purchase #5	$135.40	3.192%	$139.722	$139.72	$139.70	$139.70
Purchase #6	$192.76	3.250%	$199.0247	$199.02	$199.00	$199.00
Purchase #7	$149.51	12.776%	$168.6114	$168.61	$168.60	$168.60
7 purchase totals =	$1,013.52		$1,082.7545	$1,082.75	$1,082.70	$1,082.60