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	$91.56	3.810%	$95.0484	$95.05	$95.05	$95.00
Purchase #2	$232.94	9.285%	$254.5685	$254.57	$254.55	$254.60
Purchase #3	$181.88	9.789%	$199.6842	$199.68	$199.70	$199.70
Purchase #4	$165.38	10.207%	$182.2603	$182.26	$182.25	$182.30
Purchase #5	$17.50	3.664%	$18.1412	$18.14	$18.15	$18.10
Purchase #6	$215.39	3.232%	$222.3514	$222.35	$222.35	$222.40
Purchase #7	$223.52	12.102%	$250.5704	$250.57	$250.55	$250.60
7 purchase totals =	$1,128.17		$1,222.6244	$1,222.62	$1,222.60	$1,222.70