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	$85.47	11.144%	$94.9948	$94.99	$95.00	$95.00
Purchase #2	$57.41	5.238%	$60.4171	$60.42	$60.40	$60.40
Purchase #3	$22.25	7.372%	$23.8903	$23.89	$23.90	$23.90
Purchase #4	$60.56	3.270%	$62.5403	$62.54	$62.55	$62.50
Purchase #5	$53.64	3.464%	$55.4981	$55.50	$55.50	$55.50
Purchase #6	$159.92	5.623%	$168.9123	$168.91	$168.90	$168.90
Purchase #7	$182.30	9.192%	$199.057	$199.06	$199.05	$199.10
7 purchase totals =	$621.55		$665.3099	$665.31	$665.30	$665.30