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	$131.42	10.281%	$144.9313	$144.93	$144.95	$144.90
Purchase #2	$180.32	4.387%	$188.2306	$188.23	$188.25	$188.20
Purchase #3	$73.87	6.494%	$78.6671	$78.67	$78.65	$78.70
Purchase #4	$129.39	12.515%	$145.5832	$145.58	$145.60	$145.60
Purchase #5	$191.39	4.268%	$199.5585	$199.56	$199.55	$199.60
Purchase #6	$219.54	9.808%	$241.0725	$241.07	$241.05	$241.10
Purchase #7	$93.37	4.259%	$97.3466	$97.35	$97.35	$97.30
7 purchase totals =	$1,019.30		$1,095.3898	$1,095.39	$1,095.40	$1,095.40