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	$121.47	7.403%	$130.4624	$130.46	$130.45	$130.50
Purchase #2	$79.34	5.239%	$83.4966	$83.50	$83.50	$83.50
Purchase #3	$90.50	5.287%	$95.2847	$95.28	$95.30	$95.30
Purchase #4	$236.77	4.443%	$247.2897	$247.29	$247.30	$247.30
Purchase #5	$191.37	3.708%	$198.466	$198.47	$198.45	$198.50
Purchase #6	$157.37	8.684%	$171.036	$171.04	$171.05	$171.00
Purchase #7	$234.39	4.755%	$245.5352	$245.54	$245.55	$245.50
7 purchase totals =	$1,111.21		$1,171.5706	$1,171.58	$1,171.60	$1,171.60