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	$147.99	11.255%	$164.6463	$164.65	$164.65	$164.60
Purchase #2	$160.98	4.302%	$167.9054	$167.91	$167.90	$167.90
Purchase #3	$94.27	11.744%	$105.3411	$105.34	$105.35	$105.30
Purchase #4	$157.28	7.220%	$168.6356	$168.64	$168.65	$168.60
Purchase #5	$144.49	5.782%	$152.8444	$152.84	$152.85	$152.80
Purchase #6	$150.77	4.803%	$158.0115	$158.01	$158.00	$158.00
Purchase #7	$190.92	13.586%	$216.8584	$216.86	$216.85	$216.90
7 purchase totals =	$1,046.70		$1,134.2427	$1,134.25	$1,134.25	$1,134.10