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	$179.34	9.277%	$195.9774	$195.98	$196.00	$196.00
Purchase #2	$94.70	11.218%	$105.3234	$105.32	$105.30	$105.30
Purchase #3	$164.55	11.496%	$183.4667	$183.47	$183.45	$183.50
Purchase #4	$82.82	8.315%	$89.7065	$89.71	$89.70	$89.70
Purchase #5	$157.51	13.852%	$179.3283	$179.33	$179.35	$179.30
Purchase #6	$89.88	13.807%	$102.2897	$102.29	$102.30	$102.30
Purchase #7	$182.61	4.117%	$190.1281	$190.13	$190.15	$190.10
7 purchase totals =	$951.41		$1,046.2201	$1,046.23	$1,046.25	$1,046.20