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	$149.70	11.585%	$167.0427	$167.04	$167.05	$167.00
Purchase #2	$68.77	12.371%	$77.2775	$77.28	$77.30	$77.30
Purchase #3	$54.48	13.481%	$61.8244	$61.82	$61.80	$61.80
Purchase #4	$229.84	3.763%	$238.4889	$238.49	$238.50	$238.50
Purchase #5	$161.34	12.760%	$181.927	$181.93	$181.95	$181.90
Purchase #6	$178.55	3.271%	$184.3904	$184.39	$184.40	$184.40
Purchase #7	$102.52	3.465%	$106.0723	$106.07	$106.05	$106.10
7 purchase totals =	$945.20		$1,017.0232	$1,017.02	$1,017.05	$1,017.00