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	$85.86	10.711%	$95.0565	$95.06	$95.05	$95.10
Purchase #2	$245.94	8.575%	$267.0294	$267.03	$267.05	$267.00
Purchase #3	$52.57	12.653%	$59.2217	$59.22	$59.20	$59.20
Purchase #4	$120.74	8.851%	$131.4267	$131.43	$131.45	$131.40
Purchase #5	$187.67	13.451%	$212.9135	$212.91	$212.90	$212.90
Purchase #6	$206.84	13.840%	$235.4667	$235.47	$235.45	$235.50
Purchase #7	$148.33	10.672%	$164.1598	$164.16	$164.15	$164.20
7 purchase totals =	$1,047.95		$1,165.2743	$1,165.28	$1,165.25	$1,165.30