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	$112.50	12.688%	$126.774	$126.77	$126.75	$126.80
Purchase #2	$75.83	4.778%	$79.4532	$79.45	$79.45	$79.50
Purchase #3	$226.41	11.858%	$253.2577	$253.26	$253.25	$253.30
Purchase #4	$137.33	10.640%	$151.9419	$151.94	$151.95	$151.90
Purchase #5	$165.25	3.526%	$171.0767	$171.08	$171.10	$171.10
Purchase #6	$105.48	3.432%	$109.1001	$109.10	$109.10	$109.10
Purchase #7	$145.83	8.704%	$158.523	$158.52	$158.50	$158.50
7 purchase totals =	$968.63		$1,050.1266	$1,050.12	$1,050.10	$1,050.20