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	$76.36	7.477%	$82.0694	$82.07	$82.05	$82.10
Purchase #2	$12.53	7.242%	$13.4374	$13.44	$13.45	$13.40
Purchase #3	$72.92	7.407%	$78.3212	$78.32	$78.30	$78.30
Purchase #4	$158.56	12.663%	$178.6385	$178.64	$178.65	$178.60
Purchase #5	$245.53	7.727%	$264.5021	$264.50	$264.50	$264.50
Purchase #6	$216.70	10.487%	$239.4253	$239.43	$239.45	$239.40
Purchase #7	$139.47	6.478%	$148.5049	$148.50	$148.50	$148.50
7 purchase totals =	$922.07		$1,004.8988	$1,004.90	$1,004.90	$1,004.80