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	$200.94	10.748%	$222.537	$222.54	$222.55	$222.50
Purchase #2	$39.93	11.361%	$44.4664	$44.47	$44.45	$44.50
Purchase #3	$87.63	13.374%	$99.3496	$99.35	$99.35	$99.30
Purchase #4	$246.30	8.355%	$266.8784	$266.88	$266.90	$266.90
Purchase #5	$215.82	7.697%	$232.4317	$232.43	$232.45	$232.40
Purchase #6	$53.46	9.123%	$58.3372	$58.34	$58.35	$58.30
Purchase #7	$84.47	10.606%	$93.4289	$93.43	$93.45	$93.40
7 purchase totals =	$928.55		$1,017.4292	$1,017.44	$1,017.50	$1,017.30