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	$189.47	3.704%	$196.488	$196.49	$196.50	$196.50
Purchase #2	$116.50	10.107%	$128.2747	$128.27	$128.25	$128.30
Purchase #3	$174.36	4.317%	$181.8871	$181.89	$181.90	$181.90
Purchase #4	$194.51	13.774%	$221.3018	$221.30	$221.30	$221.30
Purchase #5	$229.52	9.507%	$251.3405	$251.34	$251.35	$251.30
Purchase #6	$136.84	9.872%	$150.3488	$150.35	$150.35	$150.30
Purchase #7	$158.53	11.527%	$176.8038	$176.80	$176.80	$176.80
7 purchase totals =	$1,199.73		$1,306.4447	$1,306.44	$1,306.45	$1,306.40