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	$133.97	12.443%	$150.6399	$150.64	$150.65	$150.60
Purchase #2	$43.75	6.366%	$46.5351	$46.54	$46.55	$46.50
Purchase #3	$91.25	11.243%	$101.5092	$101.51	$101.50	$101.50
Purchase #4	$228.55	8.213%	$247.3208	$247.32	$247.30	$247.30
Purchase #5	$130.77	10.117%	$144	$144.00	$144.00	$144.00
Purchase #6	$115.42	3.772%	$119.7736	$119.77	$119.75	$119.80
Purchase #7	$196.84	9.476%	$215.4926	$215.49	$215.50	$215.50
7 purchase totals =	$940.55		$1,025.2712	$1,025.27	$1,025.25	$1,025.20