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	$134.98	13.869%	$153.7004	$153.70	$153.70	$153.70
Purchase #2	$138.31	10.255%	$152.4937	$152.49	$152.50	$152.50
Purchase #3	$80.51	11.198%	$89.5255	$89.53	$89.55	$89.50
Purchase #4	$166.47	5.410%	$175.476	$175.48	$175.50	$175.50
Purchase #5	$97.25	5.455%	$102.555	$102.56	$102.55	$102.60
Purchase #6	$236.82	10.372%	$261.383	$261.38	$261.40	$261.40
Purchase #7	$204.87	3.498%	$212.0364	$212.04	$212.05	$212.00
7 purchase totals =	$1,059.21		$1,147.1700	$1,147.18	$1,147.25	$1,147.20