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	$202.63	11.816%	$226.5728	$226.57	$226.55	$226.60
Purchase #2	$243.27	6.512%	$259.1117	$259.11	$259.10	$259.10
Purchase #3	$37.75	12.553%	$42.4888	$42.49	$42.50	$42.50
Purchase #4	$189.56	3.479%	$196.1548	$196.15	$196.15	$196.20
Purchase #5	$54.73	13.140%	$61.9215	$61.92	$61.90	$61.90
Purchase #6	$159.40	6.189%	$169.2653	$169.27	$169.25	$169.30
Purchase #7	$146.57	5.752%	$155.0007	$155.00	$155.00	$155.00
7 purchase totals =	$1,033.91		$1,110.5156	$1,110.51	$1,110.45	$1,110.60