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	$91.66	4.531%	$95.8131	$95.81	$95.80	$95.80
Purchase #2	$114.60	4.290%	$119.5163	$119.52	$119.50	$119.50
Purchase #3	$59.94	4.102%	$62.3987	$62.40	$62.40	$62.40
Purchase #4	$232.32	7.592%	$249.9577	$249.96	$249.95	$250.00
Purchase #5	$212.71	9.804%	$233.5641	$233.56	$233.55	$233.60
Purchase #6	$231.36	13.142%	$261.7653	$261.77	$261.75	$261.80
Purchase #7	$68.61	5.507%	$72.3884	$72.39	$72.40	$72.40
7 purchase totals =	$1,011.20		$1,095.4036	$1,095.41	$1,095.35	$1,095.50