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	$144.89	4.714%	$151.7201	$151.72	$151.70	$151.70
Purchase #2	$167.81	12.192%	$188.2694	$188.27	$188.25	$188.30
Purchase #3	$164.86	5.694%	$174.2471	$174.25	$174.25	$174.20
Purchase #4	$96.56	9.518%	$105.7506	$105.75	$105.75	$105.80
Purchase #5	$234.88	4.726%	$245.9804	$245.98	$246.00	$246.00
Purchase #6	$97.43	5.621%	$102.9065	$102.91	$102.90	$102.90
Purchase #7	$72.34	3.381%	$74.7858	$74.79	$74.80	$74.80
7 purchase totals =	$978.77		$1,043.6599	$1,043.67	$1,043.65	$1,043.70