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	$71.32	7.734%	$76.8359	$76.84	$76.85	$76.80
Purchase #2	$78.34	5.145%	$82.3706	$82.37	$82.35	$82.40
Purchase #3	$180.56	5.417%	$190.3409	$190.34	$190.35	$190.30
Purchase #4	$135.48	11.681%	$151.3054	$151.31	$151.30	$151.30
Purchase #5	$73.53	11.250%	$81.8021	$81.80	$81.80	$81.80
Purchase #6	$168.34	11.671%	$187.987	$187.99	$188.00	$188.00
Purchase #7	$243.59	6.497%	$259.416	$259.42	$259.40	$259.40
7 purchase totals =	$951.16		$1,030.0579	$1,030.07	$1,030.05	$1,030.00