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	$148.84	13.236%	$168.5405	$168.54	$168.55	$168.50
Purchase #2	$190.25	5.650%	$200.9991	$201.00	$201.00	$201.00
Purchase #3	$143.65	6.429%	$152.8853	$152.89	$152.90	$152.90
Purchase #4	$227.95	11.538%	$254.2509	$254.25	$254.25	$254.30
Purchase #5	$131.35	11.244%	$146.119	$146.12	$146.10	$146.10
Purchase #6	$75.88	13.253%	$85.9364	$85.94	$85.95	$85.90
Purchase #7	$141.41	4.470%	$147.731	$147.73	$147.75	$147.70
7 purchase totals =	$1,059.33		$1,156.4622	$1,156.47	$1,156.50	$1,156.40