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	$42.30	3.201%	$43.654	$43.65	$43.65	$43.70
Purchase #2	$29.87	13.269%	$33.8335	$33.83	$33.85	$33.80
Purchase #3	$243.96	5.155%	$256.5361	$256.54	$256.55	$256.50
Purchase #4	$243.89	13.592%	$277.0395	$277.04	$277.05	$277.00
Purchase #5	$94.98	12.582%	$106.9304	$106.93	$106.95	$106.90
Purchase #6	$83.63	4.578%	$87.4586	$87.46	$87.45	$87.50
Purchase #7	$228.90	8.712%	$248.8418	$248.84	$248.85	$248.80
7 purchase totals =	$967.53		$1,054.2939	$1,054.29	$1,054.35	$1,054.20