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	$106.25	4.381%	$110.9048	$110.90	$110.90	$110.90
Purchase #2	$97.94	13.408%	$111.0718	$111.07	$111.05	$111.10
Purchase #3	$232.54	6.700%	$248.1202	$248.12	$248.10	$248.10
Purchase #4	$88.83	6.630%	$94.7194	$94.72	$94.70	$94.70
Purchase #5	$205.88	4.459%	$215.0602	$215.06	$215.05	$215.10
Purchase #6	$26.27	6.810%	$28.059	$28.06	$28.05	$28.10
Purchase #7	$211.81	11.426%	$236.0114	$236.01	$236.00	$236.00
7 purchase totals =	$969.52		$1,043.9468	$1,043.94	$1,043.85	$1,044.00